lodash.js

/**
 * @license
 * Lo-Dash 1.2.1 <http://lodash.com/>
 * Copyright 2012-2013 The Dojo Foundation <http://dojofoundation.org/>
 * Based on Underscore.js 1.4.4 <http://underscorejs.org/>
 * Copyright 2009-2013 Jeremy Ashkenas, DocumentCloud Inc.
 * Available under MIT license <http://lodash.com/license>
 */
;(function(window) {

  /** Used as a safe reference for `undefined` in pre ES5 environments */
  var undefined;

  /** Detect free variable `exports` */
  var freeExports = typeof exports == 'object' && exports;

  /** Detect free variable `module` */
  var freeModule = typeof module == 'object' && module && module.exports == freeExports && module;

  /** Detect free variable `global`, from Node.js or Browserified code, and use it as `window` */
  var freeGlobal = typeof global == 'object' && global;
  if (freeGlobal.global === freeGlobal || freeGlobal.window === freeGlobal) {
    window = freeGlobal;
  }

  /** Used to generate unique IDs */
  var idCounter = 0;

  /** Used internally to indicate various things */
  var indicatorObject = {};

  /** Used to prefix keys to avoid issues with `__proto__` and properties on `Object.prototype` */
  var keyPrefix = +new Date + '';

  /** Used as the size when optimizations are enabled for large arrays */
  var largeArraySize = 200;

  /** Used to match empty string literals in compiled template source */
  var reEmptyStringLeading = /\b__p \+= '';/g,
      reEmptyStringMiddle = /\b(__p \+=) '' \+/g,
      reEmptyStringTrailing = /(__e\(.*?\)|\b__t\)) \+\n'';/g;

  /** Used to match HTML entities */
  var reEscapedHtml = /&(?:amp|lt|gt|quot|#39);/g;

  /**
   * Used to match ES6 template delimiters
   * http://people.mozilla.org/~jorendorff/es6-draft.html#sec-7.8.6
   */
  var reEsTemplate = /\$\{([^\\}]*(?:\\.[^\\}]*)*)\}/g;

  /** Used to match regexp flags from their coerced string values */
  var reFlags = /\w*$/;

  /** Used to match "interpolate" template delimiters */
  var reInterpolate = /<%=([\s\S]+?)%>/g;

  /** Used to detect and test whitespace */
  var whitespace = (
    // whitespace
    ' \t\x0B\f\xA0\ufeff' +

    // line terminators
    '\n\r\u2028\u2029' +

    // unicode category "Zs" space separators
    '\u1680\u180e\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200a\u202f\u205f\u3000'
  );

  /** Used to match leading whitespace and zeros to be removed */
  var reLeadingSpacesAndZeros = RegExp('^[' + whitespace + ']*0+(?=.$)');

  /** Used to ensure capturing order of template delimiters */
  var reNoMatch = /($^)/;

  /** Used to match HTML characters */
  var reUnescapedHtml = /[&<>"']/g;

  /** Used to match unescaped characters in compiled string literals */
  var reUnescapedString = /['\n\r\t\u2028\u2029\\]/g;

  /** Used to assign default `context` object properties */
  var contextProps = [
    'Array', 'Boolean', 'Date', 'Error', 'Function', 'Math', 'Number', 'Object',
    'RegExp', 'String', '_', 'attachEvent', 'clearTimeout', 'isFinite', 'isNaN',
    'parseInt', 'setImmediate', 'setTimeout'
  ];

  /** Used to fix the JScript [[DontEnum]] bug */
  var shadowedProps = [
    'constructor', 'hasOwnProperty', 'isPrototypeOf', 'propertyIsEnumerable',
    'toLocaleString', 'toString', 'valueOf'
  ];

  /** Used to make template sourceURLs easier to identify */
  var templateCounter = 0;

  /** `Object#toString` result shortcuts */
  var argsClass = '[object Arguments]',
      arrayClass = '[object Array]',
      boolClass = '[object Boolean]',
      dateClass = '[object Date]',
      errorClass = '[object Error]',
      funcClass = '[object Function]',
      numberClass = '[object Number]',
      objectClass = '[object Object]',
      regexpClass = '[object RegExp]',
      stringClass = '[object String]';

  /** Used to identify object classifications that `_.clone` supports */
  var cloneableClasses = {};
  cloneableClasses[funcClass] = false;
  cloneableClasses[argsClass] = cloneableClasses[arrayClass] =
  cloneableClasses[boolClass] = cloneableClasses[dateClass] =
  cloneableClasses[numberClass] = cloneableClasses[objectClass] =
  cloneableClasses[regexpClass] = cloneableClasses[stringClass] = true;

  /** Used to determine if values are of the language type Object */
  var objectTypes = {
    'boolean': false,
    'function': true,
    'object': true,
    'number': false,
    'string': false,
    'undefined': false
  };

  /** Used to escape characters for inclusion in compiled string literals */
  var stringEscapes = {
    '\\': '\\',
    "'": "'",
    '\n': 'n',
    '\r': 'r',
    '\t': 't',
    '\u2028': 'u2028',
    '\u2029': 'u2029'
  };

  /*--------------------------------------------------------------------------*/

  /**
   * Create a new `lodash` function using the given `context` object.
   *
   * @static
   * @memberOf _
   * @category Utilities
   * @param {Object} [context=window] The context object.
   * @returns {Function} Returns the `lodash` function.
   */
  function runInContext(context) {
    // Avoid issues with some ES3 environments that attempt to use values, named
    // after built-in constructors like `Object`, for the creation of literals.
    // ES5 clears this up by stating that literals must use built-in constructors.
    // See http://es5.github.com/#x11.1.5.
    context = context ? _.defaults(window.Object(), context, _.pick(window, contextProps)) : window;

    /** Native constructor references */
    var Array = context.Array,
        Boolean = context.Boolean,
        Date = context.Date,
        Error = context.Error,
        Function = context.Function,
        Math = context.Math,
        Number = context.Number,
        Object = context.Object,
        RegExp = context.RegExp,
        String = context.String,
        TypeError = context.TypeError;

    /** Used for `Array` and `Object` method references */
    var arrayProto = Array.prototype,
        errorProto = Error.prototype,
        objectProto = Object.prototype,
        stringProto = String.prototype;

    /** Used to restore the original `_` reference in `noConflict` */
    var oldDash = context._;

    /** Used to detect if a method is native */
    var reNative = RegExp('^' +
      String(objectProto.valueOf)
        .replace(/[.*+?^${}()|[\]\\]/g, '\\$&')
        .replace(/valueOf|for [^\]]+/g, '.+?') + '$'
    );

    /** Native method shortcuts */
    var ceil = Math.ceil,
        clearTimeout = context.clearTimeout,
        concat = arrayProto.concat,
        floor = Math.floor,
        getPrototypeOf = reNative.test(getPrototypeOf = Object.getPrototypeOf) && getPrototypeOf,
        hasOwnProperty = objectProto.hasOwnProperty,
        push = arrayProto.push,
        setImmediate = context.setImmediate,
        setTimeout = context.setTimeout,
        toString = objectProto.toString;

    /* Native method shortcuts for methods with the same name as other `lodash` methods */
    var nativeBind = reNative.test(nativeBind = toString.bind) && nativeBind,
        nativeIsArray = reNative.test(nativeIsArray = Array.isArray) && nativeIsArray,
        nativeIsFinite = context.isFinite,
        nativeIsNaN = context.isNaN,
        nativeKeys = reNative.test(nativeKeys = Object.keys) && nativeKeys,
        nativeMax = Math.max,
        nativeMin = Math.min,
        nativeParseInt = context.parseInt,
        nativeRandom = Math.random,
        nativeSlice = arrayProto.slice;

    /** Detect various environments */
    var isIeOpera = reNative.test(context.attachEvent),
        isV8 = nativeBind && !/\n|true/.test(nativeBind + isIeOpera);

    /** Used to lookup a built-in constructor by [[Class]] */
    var ctorByClass = {};
    ctorByClass[arrayClass] = Array;
    ctorByClass[boolClass] = Boolean;
    ctorByClass[dateClass] = Date;
    ctorByClass[errorClass] = Error;
    ctorByClass[funcClass] = Function;
    ctorByClass[objectClass] = Object;
    ctorByClass[numberClass] = Number;
    ctorByClass[regexpClass] = RegExp;
    ctorByClass[stringClass] = String;

    /** Used to avoid iterating non-enumerable properties in IE < 9 */
    var nonEnumProps = {};
    nonEnumProps[arrayClass] = nonEnumProps[dateClass] = nonEnumProps[numberClass] = { 'constructor': true, 'toLocaleString': true, 'toString': true, 'valueOf': true };
    nonEnumProps[boolClass] = nonEnumProps[stringClass] = { 'constructor': true, 'toString': true, 'valueOf': true };
    nonEnumProps[errorClass] = nonEnumProps[funcClass] = nonEnumProps[regexpClass] = { 'constructor': true, 'toString': true };
    nonEnumProps[objectClass] = { 'constructor': true };

    (function() {
      var length = shadowedProps.length;
      while (length--) {
        var prop = shadowedProps[length];
        for (var className in nonEnumProps) {
          if (hasOwnProperty.call(nonEnumProps, className) && !hasOwnProperty.call(nonEnumProps[className], prop)) {
            nonEnumProps[className][prop] = false;
          }
        }
      }
    }());

    /*--------------------------------------------------------------------------*/

    /**
     * Creates a `lodash` object, which wraps the given `value`, to enable method
     * chaining.
     *
     * In addition to Lo-Dash methods, wrappers also have the following `Array` methods:
     * `concat`, `join`, `pop`, `push`, `reverse`, `shift`, `slice`, `sort`, `splice`,
     * and `unshift`
     *
     * Chaining is supported in custom builds as long as the `value` method is
     * implicitly or explicitly included in the build.
     *
     * The chainable wrapper functions are:
     * `after`, `assign`, `bind`, `bindAll`, `bindKey`, `chain`, `compact`,
     * `compose`, `concat`, `countBy`, `createCallback`, `debounce`, `defaults`,
     * `defer`, `delay`, `difference`, `filter`, `flatten`, `forEach`, `forIn`,
     * `forOwn`, `functions`, `groupBy`, `initial`, `intersection`, `invert`,
     * `invoke`, `keys`, `map`, `max`, `memoize`, `merge`, `min`, `object`, `omit`,
     * `once`, `pairs`, `partial`, `partialRight`, `pick`, `pluck`, `push`, `range`,
     * `reject`, `rest`, `reverse`, `shuffle`, `slice`, `sort`, `sortBy`, `splice`,
     * `tap`, `throttle`, `times`, `toArray`, `union`, `uniq`, `unshift`, `unzip`,
     * `values`, `where`, `without`, `wrap`, and `zip`
     *
     * The non-chainable wrapper functions are:
     * `clone`, `cloneDeep`, `contains`, `escape`, `every`, `find`, `has`,
     * `identity`, `indexOf`, `isArguments`, `isArray`, `isBoolean`, `isDate`,
     * `isElement`, `isEmpty`, `isEqual`, `isFinite`, `isFunction`, `isNaN`,
     * `isNull`, `isNumber`, `isObject`, `isPlainObject`, `isRegExp`, `isString`,
     * `isUndefined`, `join`, `lastIndexOf`, `mixin`, `noConflict`, `parseInt`,
     * `pop`, `random`, `reduce`, `reduceRight`, `result`, `shift`, `size`, `some`,
     * `sortedIndex`, `runInContext`, `template`, `unescape`, `uniqueId`, and `value`
     *
     * The wrapper functions `first` and `last` return wrapped values when `n` is
     * passed, otherwise they return unwrapped values.
     *
     * @name _
     * @constructor
     * @alias chain
     * @category Chaining
     * @param {Mixed} value The value to wrap in a `lodash` instance.
     * @returns {Object} Returns a `lodash` instance.
     * @example
     *
     * var wrapped = _([1, 2, 3]);
     *
     * // returns an unwrapped value
     * wrapped.reduce(function(sum, num) {
     *   return sum + num;
     * });
     * // => 6
     *
     * // returns a wrapped value
     * var squares = wrapped.map(function(num) {
     *   return num * num;
     * });
     *
     * _.isArray(squares);
     * // => false
     *
     * _.isArray(squares.value());
     * // => true
     */
    function lodash(value) {
      // don't wrap if already wrapped, even if wrapped by a different `lodash` constructor
      return (value && typeof value == 'object' && !isArray(value) && hasOwnProperty.call(value, '__wrapped__'))
       ? value
       : new lodashWrapper(value);
    }

    /**
     * An object used to flag environments features.
     *
     * @static
     * @memberOf _
     * @type Object
     */
    var support = lodash.support = {};

    (function() {
      var ctor = function() { this.x = 1; },
          object = { '0': 1, 'length': 1 },
          props = [];

      ctor.prototype = { 'valueOf': 1, 'y': 1 };
      for (var prop in new ctor) { props.push(prop); }
      for (prop in arguments) { }

      /**
       * Detect if `arguments` objects are `Object` objects (all but Narwhal and Opera < 10.5).
       *
       * @memberOf _.support
       * @type Boolean
       */
      support.argsObject = arguments.constructor == Object && !(arguments instanceof Array);

      /**
       * Detect if an `arguments` object's [[Class]] is resolvable (all but Firefox < 4, IE < 9).
       *
       * @memberOf _.support
       * @type Boolean
       */
      support.argsClass = isArguments(arguments);

      /**
       * Detect if `prototype` properties are enumerable by default.
       *
       * Firefox < 3.6, Opera > 9.50 - Opera < 11.60, and Safari < 5.1
       * (if the prototype or a property on the prototype has been set)
       * incorrectly sets a function's `prototype` property [[Enumerable]]
       * value to `true`.
       *
       * @memberOf _.support
       * @type Boolean
       */
      support.enumPrototypes = ctor.propertyIsEnumerable('prototype');

      /**
       * Detect if `Function#bind` exists and is inferred to be fast (all but V8).
       *
       * @memberOf _.support
       * @type Boolean
       */
      support.fastBind = nativeBind && !isV8;

      /**
       * Detect if own properties are iterated after inherited properties (all but IE < 9).
       *
       * @memberOf _.support
       * @type Boolean
       */
      support.ownLast = props[0] != 'x';

      /**
       * Detect if `arguments` object indexes are non-enumerable
       * (Firefox < 4, IE < 9, PhantomJS, Safari < 5.1).
       *
       * @memberOf _.support
       * @type Boolean
       */
      support.nonEnumArgs = prop != 0;

      /**
       * Detect if properties shadowing those on `Object.prototype` are non-enumerable.
       *
       * In IE < 9 an objects own properties, shadowing non-enumerable ones, are
       * made non-enumerable as well (a.k.a the JScript [[DontEnum]] bug).
       *
       * @memberOf _.support
       * @type Boolean
       */
      support.nonEnumShadows = !/valueOf/.test(props);

      /**
       * Detect if `Array#shift` and `Array#splice` augment array-like objects correctly.
       *
       * Firefox < 10, IE compatibility mode, and IE < 9 have buggy Array `shift()`
       * and `splice()` functions that fail to remove the last element, `value[0]`,
       * of array-like objects even though the `length` property is set to `0`.
       * The `shift()` method is buggy in IE 8 compatibility mode, while `splice()`
       * is buggy regardless of mode in IE < 9 and buggy in compatibility mode in IE 9.
       *
       * @memberOf _.support
       * @type Boolean
       */
      support.spliceObjects = (arrayProto.splice.call(object, 0, 1), !object[0]);

      /**
       * Detect lack of support for accessing string characters by index.
       *
       * IE < 8 can't access characters by index and IE 8 can only access
       * characters by index on string literals.
       *
       * @memberOf _.support
       * @type Boolean
       */
      support.unindexedChars = ('x'[0] + Object('x')[0]) != 'xx';

      /**
       * Detect if a DOM node's [[Class]] is resolvable (all but IE < 9)
       * and that the JS engine errors when attempting to coerce an object to
       * a string without a `toString` function.
       *
       * @memberOf _.support
       * @type Boolean
       */
      try {
        support.nodeClass = !(toString.call(document) == objectClass && !({ 'toString': 0 } + ''));
      } catch(e) {
        support.nodeClass = true;
      }
    }(1));

    /**
     * By default, the template delimiters used by Lo-Dash are similar to those in
     * embedded Ruby (ERB). Change the following template settings to use alternative
     * delimiters.
     *
     * @static
     * @memberOf _
     * @type Object
     */
    lodash.templateSettings = {

      /**
       * Used to detect `data` property values to be HTML-escaped.
       *
       * @memberOf _.templateSettings
       * @type RegExp
       */
      'escape': /<%-([\s\S]+?)%>/g,

      /**
       * Used to detect code to be evaluated.
       *
       * @memberOf _.templateSettings
       * @type RegExp
       */
      'evaluate': /<%([\s\S]+?)%>/g,

      /**
       * Used to detect `data` property values to inject.
       *
       * @memberOf _.templateSettings
       * @type RegExp
       */
      'interpolate': reInterpolate,

      /**
       * Used to reference the data object in the template text.
       *
       * @memberOf _.templateSettings
       * @type String
       */
      'variable': '',

      /**
       * Used to import variables into the compiled template.
       *
       * @memberOf _.templateSettings
       * @type Object
       */
      'imports': {

        /**
         * A reference to the `lodash` function.
         *
         * @memberOf _.templateSettings.imports
         * @type Function
         */
        '_': lodash
      }
    };

    /*--------------------------------------------------------------------------*/

    /**
     * The template used to create iterator functions.
     *
     * @private
     * @param {Object} data The data object used to populate the text.
     * @returns {String} Returns the interpolated text.
     */
    var iteratorTemplate = template(
      // the `iterable` may be reassigned by the `top` snippet
      'var index, iterable = <%= firstArg %>, ' +
      // assign the `result` variable an initial value
      'result = <%= init %>;\n' +
      // exit early if the first argument is falsey
      'if (!iterable) return result;\n' +
      // add code before the iteration branches
      '<%= top %>;' +

      // array-like iteration:
      '<% if (arrays) { %>\n' +
      'var length = iterable.length; index = -1;\n' +
      'if (<%= arrays %>) {' +

      // add support for accessing string characters by index if needed
      '  <% if (support.unindexedChars) { %>\n' +
      '  if (isString(iterable)) {\n' +
      "    iterable = iterable.split('')\n" +
      '  }' +
      '  <% } %>\n' +

      // iterate over the array-like value
      '  while (++index < length) {\n' +
      '    <%= loop %>\n' +
      '  }\n' +
      '}\n' +
      'else {' +

      // object iteration:
      // add support for iterating over `arguments` objects if needed
      '  <% } else if (support.nonEnumArgs) { %>\n' +
      '  var length = iterable.length; index = -1;\n' +
      '  if (length && isArguments(iterable)) {\n' +
      '    while (++index < length) {\n' +
      "      index += '';\n" +
      '      <%= loop %>\n' +
      '    }\n' +
      '  } else {' +
      '  <% } %>' +

      // avoid iterating over `prototype` properties in older Firefox, Opera, and Safari
      '  <% if (support.enumPrototypes) { %>\n' +
      "  var skipProto = typeof iterable == 'function';\n" +
      '  <% } %>' +

      // iterate own properties using `Object.keys` if it's fast
      '  <% if (useHas && useKeys) { %>\n' +
      '  var ownIndex = -1,\n' +
      '      ownProps = objectTypes[typeof iterable] ? keys(iterable) : [],\n' +
      '      length = ownProps.length;\n\n' +
      '  while (++ownIndex < length) {\n' +
      '    index = ownProps[ownIndex];\n' +
      "    <% if (support.enumPrototypes) { %>if (!(skipProto && index == 'prototype')) {\n  <% } %>" +
      '    <%= loop %>\n' +
      '    <% if (support.enumPrototypes) { %>}\n<% } %>' +
      '  }' +

      // else using a for-in loop
      '  <% } else { %>\n' +
      '  for (index in iterable) {<%' +
      '    if (support.enumPrototypes || useHas) { %>\n    if (<%' +
      "      if (support.enumPrototypes) { %>!(skipProto && index == 'prototype')<% }" +
      '      if (support.enumPrototypes && useHas) { %> && <% }' +
      '      if (useHas) { %>hasOwnProperty.call(iterable, index)<% }' +
      '    %>) {' +
      '    <% } %>\n' +
      '    <%= loop %>;' +
      '    <% if (support.enumPrototypes || useHas) { %>\n    }<% } %>\n' +
      '  }' +

      // Because IE < 9 can't set the `[[Enumerable]]` attribute of an
      // existing property and the `constructor` property of a prototype
      // defaults to non-enumerable, Lo-Dash skips the `constructor`
      // property when it infers it's iterating over a `prototype` object.
      '    <% if (support.nonEnumShadows) { %>\n\n' +
      '  if (iterable !== objectProto) {\n' +
      "    var ctor = iterable.constructor,\n" +
      '        proto = ctor && ctor.prototype,\n' +
      '        isProto = iterable === proto,\n' +
      '        nonEnum = nonEnumProps[objectClass];\n\n' +
      '    if (isProto) {\n' +
      "      var className = iterable === stringProto ? stringClass : iterable === errorProto ? errorClass : toString.call(iterable),\n" +
      '          nonEnum = nonEnumProps[iterable === (ctorByClass[className] && ctorByClass[className].prototype) ? className : objectClass];\n' +
      '    }\n' +
      '      <% for (k = 0; k < 7; k++) { %>\n' +
      "    index = '<%= shadowedProps[k] %>';\n" +
      '    if ((!(isProto && nonEnum[index]) && hasOwnProperty.call(iterable, index))<%' +
      '        if (!useHas) { %> || (!nonEnum[index] && iterable[index] !== objectProto[index])<% }' +
      '      %>) {\n' +
      '      <%= loop %>\n' +
      '    }' +
      '      <% } %>\n' +
      '  }' +
      '    <% } %>' +
      '  <% } %>' +
      '  <% if (arrays || support.nonEnumArgs) { %>\n}<% } %>\n' +

      // add code to the bottom of the iteration function
      '<%= bottom %>;\n' +
      // finally, return the `result`
      'return result'
    );

    /** Reusable iterator options for `assign` and `defaults` */
    var defaultsIteratorOptions = {
      'args': 'object, source, guard',
      'top':
        'var args = arguments,\n' +
        '    argsIndex = 0,\n' +
        "    argsLength = typeof guard == 'number' ? 2 : args.length;\n" +
        'while (++argsIndex < argsLength) {\n' +
        '  iterable = args[argsIndex];\n' +
        '  if (iterable && objectTypes[typeof iterable]) {',
      'loop': "if (typeof result[index] == 'undefined') result[index] = iterable[index]",
      'bottom': '  }\n}'
    };

    /** Reusable iterator options shared by `each`, `forIn`, and `forOwn` */
    var eachIteratorOptions = {
      'args': 'collection, callback, thisArg',
      'top': "callback = callback && typeof thisArg == 'undefined' ? callback : lodash.createCallback(callback, thisArg)",
      'arrays': "typeof length == 'number'",
      'loop': 'if (callback(iterable[index], index, collection) === false) return result'
    };

    /** Reusable iterator options for `forIn` and `forOwn` */
    var forOwnIteratorOptions = {
      'top': 'if (!objectTypes[typeof iterable]) return result;\n' + eachIteratorOptions.top,
      'arrays': false
    };

    /*--------------------------------------------------------------------------*/

    /**
     * Creates a function optimized to search large arrays for a given `value`,
     * starting at `fromIndex`, using strict equality for comparisons, i.e. `===`.
     *
     * @private
     * @param {Array} array The array to search.
     * @param {Mixed} value The value to search for.
     * @returns {Boolean} Returns `true`, if `value` is found, else `false`.
     */
    function cachedContains(array) {
      var length = array.length,
          isLarge = length >= largeArraySize;

      if (isLarge) {
        var cache = {},
            index = -1;

        while (++index < length) {
          var key = keyPrefix + array[index];
          (cache[key] || (cache[key] = [])).push(array[index]);
        }
      }
      return function(value) {
        if (isLarge) {
          var key = keyPrefix + value;
          return  cache[key] && indexOf(cache[key], value) > -1;
        }
        return indexOf(array, value) > -1;
      }
    }

    /**
     * Used by `_.max` and `_.min` as the default `callback` when a given
     * `collection` is a string value.
     *
     * @private
     * @param {String} value The character to inspect.
     * @returns {Number} Returns the code unit of given character.
     */
    function charAtCallback(value) {
      return value.charCodeAt(0);
    }

    /**
     * Used by `sortBy` to compare transformed `collection` values, stable sorting
     * them in ascending order.
     *
     * @private
     * @param {Object} a The object to compare to `b`.
     * @param {Object} b The object to compare to `a`.
     * @returns {Number} Returns the sort order indicator of `1` or `-1`.
     */
    function compareAscending(a, b) {
      var ai = a.index,
          bi = b.index;

      a = a.criteria;
      b = b.criteria;

      // ensure a stable sort in V8 and other engines
      // http://code.google.com/p/v8/issues/detail?id=90
      if (a !== b) {
        if (a > b || typeof a == 'undefined') {
          return 1;
        }
        if (a < b || typeof b == 'undefined') {
          return -1;
        }
      }
      return ai < bi ? -1 : 1;
    }

    /**
     * Creates a function that, when called, invokes `func` with the `this` binding
     * of `thisArg` and prepends any `partialArgs` to the arguments passed to the
     * bound function.
     *
     * @private
     * @param {Function|String} func The function to bind or the method name.
     * @param {Mixed} [thisArg] The `this` binding of `func`.
     * @param {Array} partialArgs An array of arguments to be partially applied.
     * @param {Object} [idicator] Used to indicate binding by key or partially
     *  applying arguments from the right.
     * @returns {Function} Returns the new bound function.
     */
    function createBound(func, thisArg, partialArgs, indicator) {
      var isFunc = isFunction(func),
          isPartial = !partialArgs,
          key = thisArg;

      // juggle arguments
      if (isPartial) {
        var rightIndicator = indicator;
        partialArgs = thisArg;
      }
      else if (!isFunc) {
        if (!indicator) {
          throw new TypeError;
        }
        thisArg = func;
      }

      function bound() {
        // `Function#bind` spec
        // http://es5.github.com/#x15.3.4.5
        var args = arguments,
            thisBinding = isPartial ? this : thisArg;

        if (!isFunc) {
          func = thisArg[key];
        }
        if (partialArgs.length) {
          args = args.length
            ? (args = nativeSlice.call(args), rightIndicator ? args.concat(partialArgs) : partialArgs.concat(args))
            : partialArgs;
        }
        if (this instanceof bound) {
          // ensure `new bound` is an instance of `func`
          noop.prototype = func.prototype;
          thisBinding = new noop;
          noop.prototype = null;

          // mimic the constructor's `return` behavior
          // http://es5.github.com/#x13.2.2
          var result = func.apply(thisBinding, args);
          return isObject(result) ? result : thisBinding;
        }
        return func.apply(thisBinding, args);
      }
      return bound;
    }

    /**
     * Creates compiled iteration functions.
     *
     * @private
     * @param {Object} [options1, options2, ...] The compile options object(s).
     *  arrays - A string of code to determine if the iterable is an array or array-like.
     *  useHas - A boolean to specify using `hasOwnProperty` checks in the object loop.
     *  useKeys - A boolean to specify using `_.keys` for own property iteration.
     *  args - A string of comma separated arguments the iteration function will accept.
     *  top - A string of code to execute before the iteration branches.
     *  loop - A string of code to execute in the object loop.
     *  bottom - A string of code to execute after the iteration branches.
     * @returns {Function} Returns the compiled function.
     */
    function createIterator() {
      var data = {
        // data properties
        'shadowedProps': shadowedProps,
        'support': support,

        // iterator options
        'arrays': '',
        'bottom': '',
        'init': 'iterable',
        'loop': '',
        'top': '',
        'useHas': true,
        'useKeys': !!keys
      };

      // merge options into a template data object
      for (var object, index = 0; object = arguments[index]; index++) {
        for (var key in object) {
          data[key] = object[key];
        }
      }
      var args = data.args;
      data.firstArg = /^[^,]+/.exec(args)[0];

      // create the function factory
      var factory = Function(
          'ctorByClass, errorClass, errorProto, hasOwnProperty, isArguments, ' +
          'isArray, isString, keys, lodash, objectClass, objectProto, objectTypes, ' +
          'nonEnumProps, stringClass, stringProto, toString',
        'return function(' + args + ') {\n' + iteratorTemplate(data) + '\n}'
      );
      // return the compiled function
      return factory(
        ctorByClass, errorClass, errorProto, hasOwnProperty, isArguments,
        isArray, isString, keys, lodash, objectClass, objectProto, objectTypes,
        nonEnumProps, stringClass, stringProto, toString
      );
    }

    /**
     * Used by `template` to escape characters for inclusion in compiled
     * string literals.
     *
     * @private
     * @param {String} match The matched character to escape.
     * @returns {String} Returns the escaped character.
     */
    function escapeStringChar(match) {
      return '\\' + stringEscapes[match];
    }

    /**
     * Used by `escape` to convert characters to HTML entities.
     *
     * @private
     * @param {String} match The matched character to escape.
     * @returns {String} Returns the escaped character.
     */
    function escapeHtmlChar(match) {
      return htmlEscapes[match];
    }

    /**
     * Checks if `value` is a DOM node in IE < 9.
     *
     * @private
     * @param {Mixed} value The value to check.
     * @returns {Boolean} Returns `true` if the `value` is a DOM node, else `false`.
     */
    function isNode(value) {
      // IE < 9 presents DOM nodes as `Object` objects except they have `toString`
      // methods that are `typeof` "string" and still can coerce nodes to strings
      return typeof value.toString != 'function' && typeof (value + '') == 'string';
    }

    /**
     * A fast path for creating `lodash` wrapper objects.
     *
     * @private
     * @param {Mixed} value The value to wrap in a `lodash` instance.
     * @returns {Object} Returns a `lodash` instance.
     */
    function lodashWrapper(value) {
      this.__wrapped__ = value;
    }
    // ensure `new lodashWrapper` is an instance of `lodash`
    lodashWrapper.prototype = lodash.prototype;

    /**
     * A no-operation function.
     *
     * @private
     */
    function noop() {
      // no operation performed
    }

    /**
     * A fallback implementation of `isPlainObject` which checks if a given `value`
     * is an object created by the `Object` constructor, assuming objects created
     * by the `Object` constructor have no inherited enumerable properties and that
     * there are no `Object.prototype` extensions.
     *
     * @private
     * @param {Mixed} value The value to check.
     * @returns {Boolean} Returns `true`, if `value` is a plain object, else `false`.
     */
    function shimIsPlainObject(value) {
      // avoid non-objects and false positives for `arguments` objects
      var result = false;
      if (!(value && toString.call(value) == objectClass) || (!support.argsClass && isArguments(value))) {
        return result;
      }
      // check that the constructor is `Object` (i.e. `Object instanceof Object`)
      var ctor = value.constructor;

      if (isFunction(ctor) ? ctor instanceof ctor : (support.nodeClass || !isNode(value))) {
        // IE < 9 iterates inherited properties before own properties. If the first
        // iterated property is an object's own property then there are no inherited
        // enumerable properties.
        if (support.ownLast) {
          forIn(value, function(value, key, object) {
            result = hasOwnProperty.call(object, key);
            return false;
          });
          return result === true;
        }
        // In most environments an object's own properties are iterated before
        // its inherited properties. If the last iterated property is an object's
        // own property then there are no inherited enumerable properties.
        forIn(value, function(value, key) {
          result = key;
        });
        return result === false || hasOwnProperty.call(value, result);
      }
      return result;
    }

    /**
     * Slices the `collection` from the `start` index up to, but not including,
     * the `end` index.
     *
     * Note: This function is used, instead of `Array#slice`, to support node lists
     * in IE < 9 and to ensure dense arrays are returned.
     *
     * @private
     * @param {Array|Object|String} collection The collection to slice.
     * @param {Number} start The start index.
     * @param {Number} end The end index.
     * @returns {Array} Returns the new array.
     */
    function slice(array, start, end) {
      start || (start = 0);
      if (typeof end == 'undefined') {
        end = array ? array.length : 0;
      }
      var index = -1,
          length = end - start || 0,
          result = Array(length < 0 ? 0 : length);

      while (++index < length) {
        result[index] = array[start + index];
      }
      return result;
    }

    /**
     * Used by `unescape` to convert HTML entities to characters.
     *
     * @private
     * @param {String} match The matched character to unescape.
     * @returns {String} Returns the unescaped character.
     */
    function unescapeHtmlChar(match) {
      return htmlUnescapes[match];
    }

    /*--------------------------------------------------------------------------*/

    /**
     * Checks if `value` is an `arguments` object.
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Mixed} value The value to check.
     * @returns {Boolean} Returns `true`, if the `value` is an `arguments` object, else `false`.
     * @example
     *
     * (function() { return _.isArguments(arguments); })(1, 2, 3);
     * // => true
     *
     * _.isArguments([1, 2, 3]);
     * // => false
     */
    function isArguments(value) {
      return toString.call(value) == argsClass;
    }
    // fallback for browsers that can't detect `arguments` objects by [[Class]]
    if (!support.argsClass) {
      isArguments = function(value) {
        return value ? hasOwnProperty.call(value, 'callee') : false;
      };
    }

    /**
     * Checks if `value` is an array.
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Mixed} value The value to check.
     * @returns {Boolean} Returns `true`, if the `value` is an array, else `false`.
     * @example
     *
     * (function() { return _.isArray(arguments); })();
     * // => false
     *
     * _.isArray([1, 2, 3]);
     * // => true
     */
    var isArray = nativeIsArray || function(value) {
      return value ? (typeof value == 'object' && toString.call(value) == arrayClass) : false;
    };

    /**
     * A fallback implementation of `Object.keys` which produces an array of the
     * given object's own enumerable property names.
     *
     * @private
     * @type Function
     * @param {Object} object The object to inspect.
     * @returns {Array} Returns a new array of property names.
     */
    var shimKeys = createIterator({
      'args': 'object',
      'init': '[]',
      'top': 'if (!(objectTypes[typeof object])) return result',
      'loop': 'result.push(index)'
    });

    /**
     * Creates an array composed of the own enumerable property names of `object`.
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Object} object The object to inspect.
     * @returns {Array} Returns a new array of property names.
     * @example
     *
     * _.keys({ 'one': 1, 'two': 2, 'three': 3 });
     * // => ['one', 'two', 'three'] (order is not guaranteed)
     */
    var keys = !nativeKeys ? shimKeys : function(object) {
      if (!isObject(object)) {
        return [];
      }
      if ((support.enumPrototypes && typeof object == 'function') ||
          (support.nonEnumArgs && object.length && isArguments(object))) {
        return shimKeys(object);
      }
      return nativeKeys(object);
    };

    /**
     * A function compiled to iterate `arguments` objects, arrays, objects, and
     * strings consistenly across environments, executing the `callback` for each
     * element in the `collection`. The `callback` is bound to `thisArg` and invoked
     * with three arguments; (value, index|key, collection). Callbacks may exit
     * iteration early by explicitly returning `false`.
     *
     * @private
     * @type Function
     * @param {Array|Object|String} collection The collection to iterate over.
     * @param {Function} [callback=identity] The function called per iteration.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Array|Object|String} Returns `collection`.
     */
    var each = createIterator(eachIteratorOptions);

    /**
     * Used to convert characters to HTML entities:
     *
     * Though the `>` character is escaped for symmetry, characters like `>` and `/`
     * don't require escaping in HTML and have no special meaning unless they're part
     * of a tag or an unquoted attribute value.
     * http://mathiasbynens.be/notes/ambiguous-ampersands (under "semi-related fun fact")
     */
    var htmlEscapes = {
      '&': '&amp;',
      '<': '&lt;',
      '>': '&gt;',
      '"': '&quot;',
      "'": '&#39;'
    };

    /** Used to convert HTML entities to characters */
    var htmlUnescapes = invert(htmlEscapes);

    /*--------------------------------------------------------------------------*/

    /**
     * Assigns own enumerable properties of source object(s) to the destination
     * object. Subsequent sources will overwrite property assignments of previous
     * sources. If a `callback` function is passed, it will be executed to produce
     * the assigned values. The `callback` is bound to `thisArg` and invoked with
     * two arguments; (objectValue, sourceValue).
     *
     * @static
     * @memberOf _
     * @type Function
     * @alias extend
     * @category Objects
     * @param {Object} object The destination object.
     * @param {Object} [source1, source2, ...] The source objects.
     * @param {Function} [callback] The function to customize assigning values.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Object} Returns the destination object.
     * @example
     *
     * _.assign({ 'name': 'moe' }, { 'age': 40 });
     * // => { 'name': 'moe', 'age': 40 }
     *
     * var defaults = _.partialRight(_.assign, function(a, b) {
     *   return typeof a == 'undefined' ? b : a;
     * });
     *
     * var food = { 'name': 'apple' };
     * defaults(food, { 'name': 'banana', 'type': 'fruit' });
     * // => { 'name': 'apple', 'type': 'fruit' }
     */
    var assign = createIterator(defaultsIteratorOptions, {
      'top':
        defaultsIteratorOptions.top.replace(';',
          ';\n' +
          "if (argsLength > 3 && typeof args[argsLength - 2] == 'function') {\n" +
          '  var callback = lodash.createCallback(args[--argsLength - 1], args[argsLength--], 2);\n' +
          "} else if (argsLength > 2 && typeof args[argsLength - 1] == 'function') {\n" +
          '  callback = args[--argsLength];\n' +
          '}'
        ),
      'loop': 'result[index] = callback ? callback(result[index], iterable[index]) : iterable[index]'
    });

    /**
     * Creates a clone of `value`. If `deep` is `true`, nested objects will also
     * be cloned, otherwise they will be assigned by reference. If a `callback`
     * function is passed, it will be executed to produce the cloned values. If
     * `callback` returns `undefined`, cloning will be handled by the method instead.
     * The `callback` is bound to `thisArg` and invoked with one argument; (value).
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Mixed} value The value to clone.
     * @param {Boolean} [deep=false] A flag to indicate a deep clone.
     * @param {Function} [callback] The function to customize cloning values.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @param- {Array} [stackA=[]] Tracks traversed source objects.
     * @param- {Array} [stackB=[]] Associates clones with source counterparts.
     * @returns {Mixed} Returns the cloned `value`.
     * @example
     *
     * var stooges = [
     *   { 'name': 'moe', 'age': 40 },
     *   { 'name': 'larry', 'age': 50 }
     * ];
     *
     * var shallow = _.clone(stooges);
     * shallow[0] === stooges[0];
     * // => true
     *
     * var deep = _.clone(stooges, true);
     * deep[0] === stooges[0];
     * // => false
     *
     * _.mixin({
     *   'clone': _.partialRight(_.clone, function(value) {
     *     return _.isElement(value) ? value.cloneNode(false) : undefined;
     *   })
     * });
     *
     * var clone = _.clone(document.body);
     * clone.childNodes.length;
     * // => 0
     */
    function clone(value, deep, callback, thisArg, stackA, stackB) {
      var result = value;

      // allows working with "Collections" methods without using their `callback`
      // argument, `index|key`, for this method's `callback`
      if (typeof deep == 'function') {
        thisArg = callback;
        callback = deep;
        deep = false;
      }
      if (typeof callback == 'function') {
        callback = (typeof thisArg == 'undefined')
          ? callback
          : lodash.createCallback(callback, thisArg, 1);

        result = callback(result);
        if (typeof result != 'undefined') {
          return result;
        }
        result = value;
      }
      // inspect [[Class]]
      var isObj = isObject(result);
      if (isObj) {
        var className = toString.call(result);
        if (!cloneableClasses[className] || (!support.nodeClass && isNode(result))) {
          return result;
        }
        var isArr = isArray(result);
      }
      // shallow clone
      if (!isObj || !deep) {
        return isObj
          ? (isArr ? slice(result) : assign({}, result))
          : result;
      }
      var ctor = ctorByClass[className];
      switch (className) {
        case boolClass:
        case dateClass:
          return new ctor(+result);

        case numberClass:
        case stringClass:
          return new ctor(result);

        case regexpClass:
          return ctor(result.source, reFlags.exec(result));
      }
      // check for circular references and return corresponding clone
      stackA || (stackA = []);
      stackB || (stackB = []);

      var length = stackA.length;
      while (length--) {
        if (stackA[length] == value) {
          return stackB[length];
        }
      }
      // init cloned object
      result = isArr ? ctor(result.length) : {};

      // add array properties assigned by `RegExp#exec`
      if (isArr) {
        if (hasOwnProperty.call(value, 'index')) {
          result.index = value.index;
        }
        if (hasOwnProperty.call(value, 'input')) {
          result.input = value.input;
        }
      }
      // add the source value to the stack of traversed objects
      // and associate it with its clone
      stackA.push(value);
      stackB.push(result);

      // recursively populate clone (susceptible to call stack limits)
      (isArr ? forEach : forOwn)(value, function(objValue, key) {
        result[key] = clone(objValue, deep, callback, undefined, stackA, stackB);
      });

      return result;
    }

    /**
     * Creates a deep clone of `value`. If a `callback` function is passed,
     * it will be executed to produce the cloned values. If `callback` returns
     * `undefined`, cloning will be handled by the method instead. The `callback`
     * is bound to `thisArg` and invoked with one argument; (value).
     *
     * Note: This function is loosely based on the structured clone algorithm. Functions
     * and DOM nodes are **not** cloned. The enumerable properties of `arguments` objects and
     * objects created by constructors other than `Object` are cloned to plain `Object` objects.
     * See http://www.w3.org/TR/html5/infrastructure.html#internal-structured-cloning-algorithm.
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Mixed} value The value to deep clone.
     * @param {Function} [callback] The function to customize cloning values.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Mixed} Returns the deep cloned `value`.
     * @example
     *
     * var stooges = [
     *   { 'name': 'moe', 'age': 40 },
     *   { 'name': 'larry', 'age': 50 }
     * ];
     *
     * var deep = _.cloneDeep(stooges);
     * deep[0] === stooges[0];
     * // => false
     *
     * var view = {
     *   'label': 'docs',
     *   'node': element
     * };
     *
     * var clone = _.cloneDeep(view, function(value) {
     *   return _.isElement(value) ? value.cloneNode(true) : undefined;
     * });
     *
     * clone.node == view.node;
     * // => false
     */
    function cloneDeep(value, callback, thisArg) {
      return clone(value, true, callback, thisArg);
    }

    /**
     * Assigns own enumerable properties of source object(s) to the destination
     * object for all destination properties that resolve to `undefined`. Once a
     * property is set, additional defaults of the same property will be ignored.
     *
     * @static
     * @memberOf _
     * @type Function
     * @category Objects
     * @param {Object} object The destination object.
     * @param {Object} [source1, source2, ...] The source objects.
     * @param- {Object} [guard] Allows working with `_.reduce` without using its
     *  callback's `key` and `object` arguments as sources.
     * @returns {Object} Returns the destination object.
     * @example
     *
     * var food = { 'name': 'apple' };
     * _.defaults(food, { 'name': 'banana', 'type': 'fruit' });
     * // => { 'name': 'apple', 'type': 'fruit' }
     */
    var defaults = createIterator(defaultsIteratorOptions);

    /**
     * This method is similar to `_.find`, except that it returns the key of the
     * element that passes the callback check, instead of the element itself.
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Object} object The object to search.
     * @param {Function|Object|String} [callback=identity] The function called per
     *  iteration. If a property name or object is passed, it will be used to create
     *  a "_.pluck" or "_.where" style callback, respectively.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Mixed} Returns the key of the found element, else `undefined`.
     * @example
     *
     * _.findKey({ 'a': 1, 'b': 2, 'c': 3, 'd': 4 }, function(num) {
     *   return num % 2 == 0;
     * });
     * // => 'b'
     */
    function findKey(object, callback, thisArg) {
      var result;
      callback = lodash.createCallback(callback, thisArg);
      forOwn(object, function(value, key, object) {
        if (callback(value, key, object)) {
          result = key;
          return false;
        }
      });
      return result;
    }

    /**
     * Iterates over `object`'s own and inherited enumerable properties, executing
     * the `callback` for each property. The `callback` is bound to `thisArg` and
     * invoked with three arguments; (value, key, object). Callbacks may exit iteration
     * early by explicitly returning `false`.
     *
     * @static
     * @memberOf _
     * @type Function
     * @category Objects
     * @param {Object} object The object to iterate over.
     * @param {Function} [callback=identity] The function called per iteration.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Object} Returns `object`.
     * @example
     *
     * function Dog(name) {
     *   this.name = name;
     * }
     *
     * Dog.prototype.bark = function() {
     *   alert('Woof, woof!');
     * };
     *
     * _.forIn(new Dog('Dagny'), function(value, key) {
     *   alert(key);
     * });
     * // => alerts 'name' and 'bark' (order is not guaranteed)
     */
    var forIn = createIterator(eachIteratorOptions, forOwnIteratorOptions, {
      'useHas': false
    });

    /**
     * Iterates over an object's own enumerable properties, executing the `callback`
     * for each property. The `callback` is bound to `thisArg` and invoked with three
     * arguments; (value, key, object). Callbacks may exit iteration early by explicitly
     * returning `false`.
     *
     * @static
     * @memberOf _
     * @type Function
     * @category Objects
     * @param {Object} object The object to iterate over.
     * @param {Function} [callback=identity] The function called per iteration.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Object} Returns `object`.
     * @example
     *
     * _.forOwn({ '0': 'zero', '1': 'one', 'length': 2 }, function(num, key) {
     *   alert(key);
     * });
     * // => alerts '0', '1', and 'length' (order is not guaranteed)
     */
    var forOwn = createIterator(eachIteratorOptions, forOwnIteratorOptions);

    /**
     * Creates a sorted array of all enumerable properties, own and inherited,
     * of `object` that have function values.
     *
     * @static
     * @memberOf _
     * @alias methods
     * @category Objects
     * @param {Object} object The object to inspect.
     * @returns {Array} Returns a new array of property names that have function values.
     * @example
     *
     * _.functions(_);
     * // => ['all', 'any', 'bind', 'bindAll', 'clone', 'compact', 'compose', ...]
     */
    function functions(object) {
      var result = [];
      forIn(object, function(value, key) {
        if (isFunction(value)) {
          result.push(key);
        }
      });
      return result.sort();
    }

    /**
     * Checks if the specified object `property` exists and is a direct property,
     * instead of an inherited property.
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Object} object The object to check.
     * @param {String} property The property to check for.
     * @returns {Boolean} Returns `true` if key is a direct property, else `false`.
     * @example
     *
     * _.has({ 'a': 1, 'b': 2, 'c': 3 }, 'b');
     * // => true
     */
    function has(object, property) {
      return object ? hasOwnProperty.call(object, property) : false;
    }

    /**
     * Creates an object composed of the inverted keys and values of the given `object`.
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Object} object The object to invert.
     * @returns {Object} Returns the created inverted object.
     * @example
     *
     *  _.invert({ 'first': 'moe', 'second': 'larry' });
     * // => { 'moe': 'first', 'larry': 'second' }
     */
    function invert(object) {
      var index = -1,
          props = keys(object),
          length = props.length,
          result = {};

      while (++index < length) {
        var key = props[index];
        result[object[key]] = key;
      }
      return result;
    }

    /**
     * Checks if `value` is a boolean value.
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Mixed} value The value to check.
     * @returns {Boolean} Returns `true`, if the `value` is a boolean value, else `false`.
     * @example
     *
     * _.isBoolean(null);
     * // => false
     */
    function isBoolean(value) {
      return value === true || value === false || toString.call(value) == boolClass;
    }

    /**
     * Checks if `value` is a date.
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Mixed} value The value to check.
     * @returns {Boolean} Returns `true`, if the `value` is a date, else `false`.
     * @example
     *
     * _.isDate(new Date);
     * // => true
     */
    function isDate(value) {
      return value ? (typeof value == 'object' && toString.call(value) == dateClass) : false;
    }

    /**
     * Checks if `value` is a DOM element.
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Mixed} value The value to check.
     * @returns {Boolean} Returns `true`, if the `value` is a DOM element, else `false`.
     * @example
     *
     * _.isElement(document.body);
     * // => true
     */
    function isElement(value) {
      return value ? value.nodeType === 1 : false;
    }

    /**
     * Checks if `value` is empty. Arrays, strings, or `arguments` objects with a
     * length of `0` and objects with no own enumerable properties are considered
     * "empty".
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Array|Object|String} value The value to inspect.
     * @returns {Boolean} Returns `true`, if the `value` is empty, else `false`.
     * @example
     *
     * _.isEmpty([1, 2, 3]);
     * // => false
     *
     * _.isEmpty({});
     * // => true
     *
     * _.isEmpty('');
     * // => true
     */
    function isEmpty(value) {
      var result = true;
      if (!value) {
        return result;
      }
      var className = toString.call(value),
          length = value.length;

      if ((className == arrayClass || className == stringClass ||
          (support.argsClass ? className == argsClass : isArguments(value))) ||
          (className == objectClass && typeof length == 'number' && isFunction(value.splice))) {
        return !length;
      }
      forOwn(value, function() {
        return (result = false);
      });
      return result;
    }

    /**
     * Performs a deep comparison between two values to determine if they are
     * equivalent to each other. If `callback` is passed, it will be executed to
     * compare values. If `callback` returns `undefined`, comparisons will be handled
     * by the method instead. The `callback` is bound to `thisArg` and invoked with
     * two arguments; (a, b).
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Mixed} a The value to compare.
     * @param {Mixed} b The other value to compare.
     * @param {Function} [callback] The function to customize comparing values.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @param- {Array} [stackA=[]] Tracks traversed `a` objects.
     * @param- {Array} [stackB=[]] Tracks traversed `b` objects.
     * @returns {Boolean} Returns `true`, if the values are equivalent, else `false`.
     * @example
     *
     * var moe = { 'name': 'moe', 'age': 40 };
     * var copy = { 'name': 'moe', 'age': 40 };
     *
     * moe == copy;
     * // => false
     *
     * _.isEqual(moe, copy);
     * // => true
     *
     * var words = ['hello', 'goodbye'];
     * var otherWords = ['hi', 'goodbye'];
     *
     * _.isEqual(words, otherWords, function(a, b) {
     *   var reGreet = /^(?:hello|hi)$/i,
     *       aGreet = _.isString(a) && reGreet.test(a),
     *       bGreet = _.isString(b) && reGreet.test(b);
     *
     *   return (aGreet || bGreet) ? (aGreet == bGreet) : undefined;
     * });
     * // => true
     */
    function isEqual(a, b, callback, thisArg, stackA, stackB) {
      // used to indicate that when comparing objects, `a` has at least the properties of `b`
      var whereIndicator = callback === indicatorObject;
      if (typeof callback == 'function' && !whereIndicator) {
        callback = lodash.createCallback(callback, thisArg, 2);
        var result = callback(a, b);
        if (typeof result != 'undefined') {
          return !!result;
        }
      }
      // exit early for identical values
      if (a === b) {
        // treat `+0` vs. `-0` as not equal
        return a !== 0 || (1 / a == 1 / b);
      }
      var type = typeof a,
          otherType = typeof b;

      // exit early for unlike primitive values
      if (a === a &&
          (!a || (type != 'function' && type != 'object')) &&
          (!b || (otherType != 'function' && otherType != 'object'))) {
        return false;
      }
      // exit early for `null` and `undefined`, avoiding ES3's Function#call behavior
      // http://es5.github.com/#x15.3.4.4
      if (a == null || b == null) {
        return a === b;
      }
      // compare [[Class]] names
      var className = toString.call(a),
          otherClass = toString.call(b);

      if (className == argsClass) {
        className = objectClass;
      }
      if (otherClass == argsClass) {
        otherClass = objectClass;
      }
      if (className != otherClass) {
        return false;
      }
      switch (className) {
        case boolClass:
        case dateClass:
          // coerce dates and booleans to numbers, dates to milliseconds and booleans
          // to `1` or `0`, treating invalid dates coerced to `NaN` as not equal
          return +a == +b;

        case numberClass:
          // treat `NaN` vs. `NaN` as equal
          return (a != +a)
            ? b != +b
            // but treat `+0` vs. `-0` as not equal
            : (a == 0 ? (1 / a == 1 / b) : a == +b);

        case regexpClass:
        case stringClass:
          // coerce regexes to strings (http://es5.github.com/#x15.10.6.4)
          // treat string primitives and their corresponding object instances as equal
          return a == String(b);
      }
      var isArr = className == arrayClass;
      if (!isArr) {
        // unwrap any `lodash` wrapped values
        if (hasOwnProperty.call(a, '__wrapped__ ') || hasOwnProperty.call(b, '__wrapped__')) {
          return isEqual(a.__wrapped__ || a, b.__wrapped__ || b, callback, thisArg, stackA, stackB);
        }
        // exit for functions and DOM nodes
        if (className != objectClass || (!support.nodeClass && (isNode(a) || isNode(b)))) {
          return false;
        }
        // in older versions of Opera, `arguments` objects have `Array` constructors
        var ctorA = !support.argsObject && isArguments(a) ? Object : a.constructor,
            ctorB = !support.argsObject && isArguments(b) ? Object : b.constructor;

        // non `Object` object instances with different constructors are not equal
        if (ctorA != ctorB && !(
              isFunction(ctorA) && ctorA instanceof ctorA &&
              isFunction(ctorB) && ctorB instanceof ctorB
            )) {
          return false;
        }
      }
      // assume cyclic structures are equal
      // the algorithm for detecting cyclic structures is adapted from ES 5.1
      // section 15.12.3, abstract operation `JO` (http://es5.github.com/#x15.12.3)
      stackA || (stackA = []);
      stackB || (stackB = []);

      var length = stackA.length;
      while (length--) {
        if (stackA[length] == a) {
          return stackB[length] == b;
        }
      }
      var size = 0;
      result = true;

      // add `a` and `b` to the stack of traversed objects
      stackA.push(a);
      stackB.push(b);

      // recursively compare objects and arrays (susceptible to call stack limits)
      if (isArr) {
        length = a.length;
        size = b.length;

        // compare lengths to determine if a deep comparison is necessary
        result = size == a.length;
        if (!result && !whereIndicator) {
          return result;
        }
        // deep compare the contents, ignoring non-numeric properties
        while (size--) {
          var index = length,
              value = b[size];

          if (whereIndicator) {
            while (index--) {
              if ((result = isEqual(a[index], value, callback, thisArg, stackA, stackB))) {
                break;
              }
            }
          } else if (!(result = isEqual(a[size], value, callback, thisArg, stackA, stackB))) {
            break;
          }
        }
        return result;
      }
      // deep compare objects using `forIn`, instead of `forOwn`, to avoid `Object.keys`
      // which, in this case, is more costly
      forIn(b, function(value, key, b) {
        if (hasOwnProperty.call(b, key)) {
          // count the number of properties.
          size++;
          // deep compare each property value.
          return (result = hasOwnProperty.call(a, key) && isEqual(a[key], value, callback, thisArg, stackA, stackB));
        }
      });

      if (result && !whereIndicator) {
        // ensure both objects have the same number of properties
        forIn(a, function(value, key, a) {
          if (hasOwnProperty.call(a, key)) {
            // `size` will be `-1` if `a` has more properties than `b`
            return (result = --size > -1);
          }
        });
      }
      return result;
    }

    /**
     * Checks if `value` is, or can be coerced to, a finite number.
     *
     * Note: This is not the same as native `isFinite`, which will return true for
     * booleans and empty strings. See http://es5.github.com/#x15.1.2.5.
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Mixed} value The value to check.
     * @returns {Boolean} Returns `true`, if the `value` is finite, else `false`.
     * @example
     *
     * _.isFinite(-101);
     * // => true
     *
     * _.isFinite('10');
     * // => true
     *
     * _.isFinite(true);
     * // => false
     *
     * _.isFinite('');
     * // => false
     *
     * _.isFinite(Infinity);
     * // => false
     */
    function isFinite(value) {
      return nativeIsFinite(value) && !nativeIsNaN(parseFloat(value));
    }

    /**
     * Checks if `value` is a function.
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Mixed} value The value to check.
     * @returns {Boolean} Returns `true`, if the `value` is a function, else `false`.
     * @example
     *
     * _.isFunction(_);
     * // => true
     */
    function isFunction(value) {
      return typeof value == 'function';
    }
    // fallback for older versions of Chrome and Safari
    if (isFunction(/x/)) {
      isFunction = function(value) {
        return typeof value == 'function' && toString.call(value) == funcClass;
      };
    }

    /**
     * Checks if `value` is the language type of Object.
     * (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Mixed} value The value to check.
     * @returns {Boolean} Returns `true`, if the `value` is an object, else `false`.
     * @example
     *
     * _.isObject({});
     * // => true
     *
     * _.isObject([1, 2, 3]);
     * // => true
     *
     * _.isObject(1);
     * // => false
     */
    function isObject(value) {
      // check if the value is the ECMAScript language type of Object
      // http://es5.github.com/#x8
      // and avoid a V8 bug
      // http://code.google.com/p/v8/issues/detail?id=2291
      return !!(value && objectTypes[typeof value]);
    }

    /**
     * Checks if `value` is `NaN`.
     *
     * Note: This is not the same as native `isNaN`, which will return `true` for
     * `undefined` and other values. See http://es5.github.com/#x15.1.2.4.
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Mixed} value The value to check.
     * @returns {Boolean} Returns `true`, if the `value` is `NaN`, else `false`.
     * @example
     *
     * _.isNaN(NaN);
     * // => true
     *
     * _.isNaN(new Number(NaN));
     * // => true
     *
     * isNaN(undefined);
     * // => true
     *
     * _.isNaN(undefined);
     * // => false
     */
    function isNaN(value) {
      // `NaN` as a primitive is the only value that is not equal to itself
      // (perform the [[Class]] check first to avoid errors with some host objects in IE)
      return isNumber(value) && value != +value
    }

    /**
     * Checks if `value` is `null`.
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Mixed} value The value to check.
     * @returns {Boolean} Returns `true`, if the `value` is `null`, else `false`.
     * @example
     *
     * _.isNull(null);
     * // => true
     *
     * _.isNull(undefined);
     * // => false
     */
    function isNull(value) {
      return value === null;
    }

    /**
     * Checks if `value` is a number.
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Mixed} value The value to check.
     * @returns {Boolean} Returns `true`, if the `value` is a number, else `false`.
     * @example
     *
     * _.isNumber(8.4 * 5);
     * // => true
     */
    function isNumber(value) {
      return typeof value == 'number' || toString.call(value) == numberClass;
    }

    /**
     * Checks if a given `value` is an object created by the `Object` constructor.
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Mixed} value The value to check.
     * @returns {Boolean} Returns `true`, if `value` is a plain object, else `false`.
     * @example
     *
     * function Stooge(name, age) {
     *   this.name = name;
     *   this.age = age;
     * }
     *
     * _.isPlainObject(new Stooge('moe', 40));
     * // => false
     *
     * _.isPlainObject([1, 2, 3]);
     * // => false
     *
     * _.isPlainObject({ 'name': 'moe', 'age': 40 });
     * // => true
     */
    var isPlainObject = !getPrototypeOf ? shimIsPlainObject : function(value) {
      if (!(value && toString.call(value) == objectClass) || (!support.argsClass && isArguments(value))) {
        return false;
      }
      var valueOf = value.valueOf,
          objProto = typeof valueOf == 'function' && (objProto = getPrototypeOf(valueOf)) && getPrototypeOf(objProto);

      return objProto
        ? (value == objProto || getPrototypeOf(value) == objProto)
        : shimIsPlainObject(value);
    };

    /**
     * Checks if `value` is a regular expression.
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Mixed} value The value to check.
     * @returns {Boolean} Returns `true`, if the `value` is a regular expression, else `false`.
     * @example
     *
     * _.isRegExp(/moe/);
     * // => true
     */
    function isRegExp(value) {
      return !!(value && objectTypes[typeof value]) && toString.call(value) == regexpClass;
    }

    /**
     * Checks if `value` is a string.
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Mixed} value The value to check.
     * @returns {Boolean} Returns `true`, if the `value` is a string, else `false`.
     * @example
     *
     * _.isString('moe');
     * // => true
     */
    function isString(value) {
      return typeof value == 'string' || toString.call(value) == stringClass;
    }

    /**
     * Checks if `value` is `undefined`.
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Mixed} value The value to check.
     * @returns {Boolean} Returns `true`, if the `value` is `undefined`, else `false`.
     * @example
     *
     * _.isUndefined(void 0);
     * // => true
     */
    function isUndefined(value) {
      return typeof value == 'undefined';
    }

    /**
     * Recursively merges own enumerable properties of the source object(s), that
     * don't resolve to `undefined`, into the destination object. Subsequent sources
     * will overwrite property assignments of previous sources. If a `callback` function
     * is passed, it will be executed to produce the merged values of the destination
     * and source properties. If `callback` returns `undefined`, merging will be
     * handled by the method instead. The `callback` is bound to `thisArg` and
     * invoked with two arguments; (objectValue, sourceValue).
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Object} object The destination object.
     * @param {Object} [source1, source2, ...] The source objects.
     * @param {Function} [callback] The function to customize merging properties.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @param- {Object} [deepIndicator] Indicates that `stackA` and `stackB` are
     *  arrays of traversed objects, instead of source objects.
     * @param- {Array} [stackA=[]] Tracks traversed source objects.
     * @param- {Array} [stackB=[]] Associates values with source counterparts.
     * @returns {Object} Returns the destination object.
     * @example
     *
     * var names = {
     *   'stooges': [
     *     { 'name': 'moe' },
     *     { 'name': 'larry' }
     *   ]
     * };
     *
     * var ages = {
     *   'stooges': [
     *     { 'age': 40 },
     *     { 'age': 50 }
     *   ]
     * };
     *
     * _.merge(names, ages);
     * // => { 'stooges': [{ 'name': 'moe', 'age': 40 }, { 'name': 'larry', 'age': 50 }] }
     *
     * var food = {
     *   'fruits': ['apple'],
     *   'vegetables': ['beet']
     * };
     *
     * var otherFood = {
     *   'fruits': ['banana'],
     *   'vegetables': ['carrot']
     * };
     *
     * _.merge(food, otherFood, function(a, b) {
     *   return _.isArray(a) ? a.concat(b) : undefined;
     * });
     * // => { 'fruits': ['apple', 'banana'], 'vegetables': ['beet', 'carrot] }
     */
    function merge(object, source, deepIndicator) {
      var args = arguments,
          index = 0,
          length = 2;

      if (!isObject(object)) {
        return object;
      }
      if (deepIndicator === indicatorObject) {
        var callback = args[3],
            stackA = args[4],
            stackB = args[5];
      } else {
        stackA = [];
        stackB = [];

        // allows working with `_.reduce` and `_.reduceRight` without
        // using their `callback` arguments, `index|key` and `collection`
        if (typeof deepIndicator != 'number') {
          length = args.length;
        }
        if (length > 3 && typeof args[length - 2] == 'function') {
          callback = lodash.createCallback(args[--length - 1], args[length--], 2);
        } else if (length > 2 && typeof args[length - 1] == 'function') {
          callback = args[--length];
        }
      }
      while (++index < length) {
        (isArray(args[index]) ? forEach : forOwn)(args[index], function(source, key) {
          var found,
              isArr,
              result = source,
              value = object[key];

          if (source && ((isArr = isArray(source)) || isPlainObject(source))) {
            // avoid merging previously merged cyclic sources
            var stackLength = stackA.length;
            while (stackLength--) {
              if ((found = stackA[stackLength] == source)) {
                value = stackB[stackLength];
                break;
              }
            }
            if (!found) {
              var isShallow;
              if (callback) {
                result = callback(value, source);
                if ((isShallow = typeof result != 'undefined')) {
                  value = result;
                }
              }
              if (!isShallow) {
                value = isArr
                  ? (isArray(value) ? value : [])
                  : (isPlainObject(value) ? value : {});
              }
              // add `source` and associated `value` to the stack of traversed objects
              stackA.push(source);
              stackB.push(value);

              // recursively merge objects and arrays (susceptible to call stack limits)
              if (!isShallow) {
                value = merge(value, source, indicatorObject, callback, stackA, stackB);
              }
            }
          }
          else {
            if (callback) {
              result = callback(value, source);
              if (typeof result == 'undefined') {
                result = source;
              }
            }
            if (typeof result != 'undefined') {
              value = result;
            }
          }
          object[key] = value;
        });
      }
      return object;
    }

    /**
     * Creates a shallow clone of `object` excluding the specified properties.
     * Property names may be specified as individual arguments or as arrays of
     * property names. If a `callback` function is passed, it will be executed
     * for each property in the `object`, omitting the properties `callback`
     * returns truthy for. The `callback` is bound to `thisArg` and invoked
     * with three arguments; (value, key, object).
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Object} object The source object.
     * @param {Function|String} callback|[prop1, prop2, ...] The properties to omit
     *  or the function called per iteration.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Object} Returns an object without the omitted properties.
     * @example
     *
     * _.omit({ 'name': 'moe', 'age': 40 }, 'age');
     * // => { 'name': 'moe' }
     *
     * _.omit({ 'name': 'moe', 'age': 40 }, function(value) {
     *   return typeof value == 'number';
     * });
     * // => { 'name': 'moe' }
     */
    function omit(object, callback, thisArg) {
      var isFunc = typeof callback == 'function',
          result = {};

      if (isFunc) {
        callback = lodash.createCallback(callback, thisArg);
      } else {
        var props = concat.apply(arrayProto, nativeSlice.call(arguments, 1));
      }
      forIn(object, function(value, key, object) {
        if (isFunc
              ? !callback(value, key, object)
              : indexOf(props, key) < 0
            ) {
          result[key] = value;
        }
      });
      return result;
    }

    /**
     * Creates a two dimensional array of the given object's key-value pairs,
     * i.e. `[[key1, value1], [key2, value2]]`.
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Object} object The object to inspect.
     * @returns {Array} Returns new array of key-value pairs.
     * @example
     *
     * _.pairs({ 'moe': 30, 'larry': 40 });
     * // => [['moe', 30], ['larry', 40]] (order is not guaranteed)
     */
    function pairs(object) {
      var index = -1,
          props = keys(object),
          length = props.length,
          result = Array(length);

      while (++index < length) {
        var key = props[index];
        result[index] = [key, object[key]];
      }
      return result;
    }

    /**
     * Creates a shallow clone of `object` composed of the specified properties.
     * Property names may be specified as individual arguments or as arrays of property
     * names. If `callback` is passed, it will be executed for each property in the
     * `object`, picking the properties `callback` returns truthy for. The `callback`
     * is bound to `thisArg` and invoked with three arguments; (value, key, object).
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Object} object The source object.
     * @param {Array|Function|String} callback|[prop1, prop2, ...] The function called
     *  per iteration or properties to pick, either as individual arguments or arrays.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Object} Returns an object composed of the picked properties.
     * @example
     *
     * _.pick({ 'name': 'moe', '_userid': 'moe1' }, 'name');
     * // => { 'name': 'moe' }
     *
     * _.pick({ 'name': 'moe', '_userid': 'moe1' }, function(value, key) {
     *   return key.charAt(0) != '_';
     * });
     * // => { 'name': 'moe' }
     */
    function pick(object, callback, thisArg) {
      var result = {};
      if (typeof callback != 'function') {
        var index = -1,
            props = concat.apply(arrayProto, nativeSlice.call(arguments, 1)),
            length = isObject(object) ? props.length : 0;

        while (++index < length) {
          var key = props[index];
          if (key in object) {
            result[key] = object[key];
          }
        }
      } else {
        callback = lodash.createCallback(callback, thisArg);
        forIn(object, function(value, key, object) {
          if (callback(value, key, object)) {
            result[key] = value;
          }
        });
      }
      return result;
    }

    /**
     * Creates an array composed of the own enumerable property values of `object`.
     *
     * @static
     * @memberOf _
     * @category Objects
     * @param {Object} object The object to inspect.
     * @returns {Array} Returns a new array of property values.
     * @example
     *
     * _.values({ 'one': 1, 'two': 2, 'three': 3 });
     * // => [1, 2, 3] (order is not guaranteed)
     */
    function values(object) {
      var index = -1,
          props = keys(object),
          length = props.length,
          result = Array(length);

      while (++index < length) {
        result[index] = object[props[index]];
      }
      return result;
    }

    /*--------------------------------------------------------------------------*/

    /**
     * Creates an array of elements from the specified indexes, or keys, of the
     * `collection`. Indexes may be specified as individual arguments or as arrays
     * of indexes.
     *
     * @static
     * @memberOf _
     * @category Collections
     * @param {Array|Object|String} collection The collection to iterate over.
     * @param {Array|Number|String} [index1, index2, ...] The indexes of
     *  `collection` to retrieve, either as individual arguments or arrays.
     * @returns {Array} Returns a new array of elements corresponding to the
     *  provided indexes.
     * @example
     *
     * _.at(['a', 'b', 'c', 'd', 'e'], [0, 2, 4]);
     * // => ['a', 'c', 'e']
     *
     * _.at(['moe', 'larry', 'curly'], 0, 2);
     * // => ['moe', 'curly']
     */
    function at(collection) {
      var index = -1,
          props = concat.apply(arrayProto, nativeSlice.call(arguments, 1)),
          length = props.length,
          result = Array(length);

      if (support.unindexedChars && isString(collection)) {
        collection = collection.split('');
      }
      while(++index < length) {
        result[index] = collection[props[index]];
      }
      return result;
    }

    /**
     * Checks if a given `target` element is present in a `collection` using strict
     * equality for comparisons, i.e. `===`. If `fromIndex` is negative, it is used
     * as the offset from the end of the collection.
     *
     * @static
     * @memberOf _
     * @alias include
     * @category Collections
     * @param {Array|Object|String} collection The collection to iterate over.
     * @param {Mixed} target The value to check for.
     * @param {Number} [fromIndex=0] The index to search from.
     * @returns {Boolean} Returns `true` if the `target` element is found, else `false`.
     * @example
     *
     * _.contains([1, 2, 3], 1);
     * // => true
     *
     * _.contains([1, 2, 3], 1, 2);
     * // => false
     *
     * _.contains({ 'name': 'moe', 'age': 40 }, 'moe');
     * // => true
     *
     * _.contains('curly', 'ur');
     * // => true
     */
    function contains(collection, target, fromIndex) {
      var index = -1,
          length = collection ? collection.length : 0,
          result = false;

      fromIndex = (fromIndex < 0 ? nativeMax(0, length + fromIndex) : fromIndex) || 0;
      if (typeof length == 'number') {
        result = (isString(collection)
          ? collection.indexOf(target, fromIndex)
          : indexOf(collection, target, fromIndex)
        ) > -1;
      } else {
        each(collection, function(value) {
          if (++index >= fromIndex) {
            return !(result = value === target);
          }
        });
      }
      return result;
    }

    /**
     * Creates an object composed of keys returned from running each element of the
     * `collection` through the given `callback`. The corresponding value of each key
     * is the number of times the key was returned by the `callback`. The `callback`
     * is bound to `thisArg` and invoked with three arguments; (value, index|key, collection).
     *
     * If a property name is passed for `callback`, the created "_.pluck" style
     * callback will return the property value of the given element.
     *
     * If an object is passed for `callback`, the created "_.where" style callback
     * will return `true` for elements that have the properties of the given object,
     * else `false`.
     *
     * @static
     * @memberOf _
     * @category Collections
     * @param {Array|Object|String} collection The collection to iterate over.
     * @param {Function|Object|String} [callback=identity] The function called per
     *  iteration. If a property name or object is passed, it will be used to create
     *  a "_.pluck" or "_.where" style callback, respectively.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Object} Returns the composed aggregate object.
     * @example
     *
     * _.countBy([4.3, 6.1, 6.4], function(num) { return Math.floor(num); });
     * // => { '4': 1, '6': 2 }
     *
     * _.countBy([4.3, 6.1, 6.4], function(num) { return this.floor(num); }, Math);
     * // => { '4': 1, '6': 2 }
     *
     * _.countBy(['one', 'two', 'three'], 'length');
     * // => { '3': 2, '5': 1 }
     */
    function countBy(collection, callback, thisArg) {
      var result = {};
      callback = lodash.createCallback(callback, thisArg);

      forEach(collection, function(value, key, collection) {
        key = String(callback(value, key, collection));
        (hasOwnProperty.call(result, key) ? result[key]++ : result[key] = 1);
      });
      return result;
    }

    /**
     * Checks if the `callback` returns a truthy value for **all** elements of a
     * `collection`. The `callback` is bound to `thisArg` and invoked with three
     * arguments; (value, index|key, collection).
     *
     * If a property name is passed for `callback`, the created "_.pluck" style
     * callback will return the property value of the given element.
     *
     * If an object is passed for `callback`, the created "_.where" style callback
     * will return `true` for elements that have the properties of the given object,
     * else `false`.
     *
     * @static
     * @memberOf _
     * @alias all
     * @category Collections
     * @param {Array|Object|String} collection The collection to iterate over.
     * @param {Function|Object|String} [callback=identity] The function called per
     *  iteration. If a property name or object is passed, it will be used to create
     *  a "_.pluck" or "_.where" style callback, respectively.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Boolean} Returns `true` if all elements pass the callback check,
     *  else `false`.
     * @example
     *
     * _.every([true, 1, null, 'yes'], Boolean);
     * // => false
     *
     * var stooges = [
     *   { 'name': 'moe', 'age': 40 },
     *   { 'name': 'larry', 'age': 50 }
     * ];
     *
     * // using "_.pluck" callback shorthand
     * _.every(stooges, 'age');
     * // => true
     *
     * // using "_.where" callback shorthand
     * _.every(stooges, { 'age': 50 });
     * // => false
     */
    function every(collection, callback, thisArg) {
      var result = true;
      callback = lodash.createCallback(callback, thisArg);

      if (isArray(collection)) {
        var index = -1,
            length = collection.length;

        while (++index < length) {
          if (!(result = !!callback(collection[index], index, collection))) {
            break;
          }
        }
      } else {
        each(collection, function(value, index, collection) {
          return (result = !!callback(value, index, collection));
        });
      }
      return result;
    }

    /**
     * Examines each element in a `collection`, returning an array of all elements
     * the `callback` returns truthy for. The `callback` is bound to `thisArg` and
     * invoked with three arguments; (value, index|key, collection).
     *
     * If a property name is passed for `callback`, the created "_.pluck" style
     * callback will return the property value of the given element.
     *
     * If an object is passed for `callback`, the created "_.where" style callback
     * will return `true` for elements that have the properties of the given object,
     * else `false`.
     *
     * @static
     * @memberOf _
     * @alias select
     * @category Collections
     * @param {Array|Object|String} collection The collection to iterate over.
     * @param {Function|Object|String} [callback=identity] The function called per
     *  iteration. If a property name or object is passed, it will be used to create
     *  a "_.pluck" or "_.where" style callback, respectively.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Array} Returns a new array of elements that passed the callback check.
     * @example
     *
     * var evens = _.filter([1, 2, 3, 4, 5, 6], function(num) { return num % 2 == 0; });
     * // => [2, 4, 6]
     *
     * var food = [
     *   { 'name': 'apple',  'organic': false, 'type': 'fruit' },
     *   { 'name': 'carrot', 'organic': true,  'type': 'vegetable' }
     * ];
     *
     * // using "_.pluck" callback shorthand
     * _.filter(food, 'organic');
     * // => [{ 'name': 'carrot', 'organic': true, 'type': 'vegetable' }]
     *
     * // using "_.where" callback shorthand
     * _.filter(food, { 'type': 'fruit' });
     * // => [{ 'name': 'apple', 'organic': false, 'type': 'fruit' }]
     */
    function filter(collection, callback, thisArg) {
      var result = [];
      callback = lodash.createCallback(callback, thisArg);

      if (isArray(collection)) {
        var index = -1,
            length = collection.length;

        while (++index < length) {
          var value = collection[index];
          if (callback(value, index, collection)) {
            result.push(value);
          }
        }
      } else {
        each(collection, function(value, index, collection) {
          if (callback(value, index, collection)) {
            result.push(value);
          }
        });
      }
      return result;
    }

    /**
     * Examines each element in a `collection`, returning the first that the `callback`
     * returns truthy for. The `callback` is bound to `thisArg` and invoked with three
     * arguments; (value, index|key, collection).
     *
     * If a property name is passed for `callback`, the created "_.pluck" style
     * callback will return the property value of the given element.
     *
     * If an object is passed for `callback`, the created "_.where" style callback
     * will return `true` for elements that have the properties of the given object,
     * else `false`.
     *
     * @static
     * @memberOf _
     * @alias detect
     * @category Collections
     * @param {Array|Object|String} collection The collection to iterate over.
     * @param {Function|Object|String} [callback=identity] The function called per
     *  iteration. If a property name or object is passed, it will be used to create
     *  a "_.pluck" or "_.where" style callback, respectively.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Mixed} Returns the found element, else `undefined`.
     * @example
     *
     * _.find([1, 2, 3, 4], function(num) {
     *   return num % 2 == 0;
     * });
     * // => 2
     *
     * var food = [
     *   { 'name': 'apple',  'organic': false, 'type': 'fruit' },
     *   { 'name': 'banana', 'organic': true,  'type': 'fruit' },
     *   { 'name': 'beet',   'organic': false, 'type': 'vegetable' }
     * ];
     *
     * // using "_.where" callback shorthand
     * _.find(food, { 'type': 'vegetable' });
     * // => { 'name': 'beet', 'organic': false, 'type': 'vegetable' }
     *
     * // using "_.pluck" callback shorthand
     * _.find(food, 'organic');
     * // => { 'name': 'banana', 'organic': true, 'type': 'fruit' }
     */
    function find(collection, callback, thisArg) {
      callback = lodash.createCallback(callback, thisArg);

      if (isArray(collection)) {
        var index = -1,
            length = collection.length;

        while (++index < length) {
          var value = collection[index];
          if (callback(value, index, collection)) {
            return value;
          }
        }
      } else {
        var result;
        each(collection, function(value, index, collection) {
          if (callback(value, index, collection)) {
            result = value;
            return false;
          }
        });
        return result;
      }
    }

    /**
     * Iterates over a `collection`, executing the `callback` for each element in
     * the `collection`. The `callback` is bound to `thisArg` and invoked with three
     * arguments; (value, index|key, collection). Callbacks may exit iteration early
     * by explicitly returning `false`.
     *
     * @static
     * @memberOf _
     * @alias each
     * @category Collections
     * @param {Array|Object|String} collection The collection to iterate over.
     * @param {Function} [callback=identity] The function called per iteration.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Array|Object|String} Returns `collection`.
     * @example
     *
     * _([1, 2, 3]).forEach(alert).join(',');
     * // => alerts each number and returns '1,2,3'
     *
     * _.forEach({ 'one': 1, 'two': 2, 'three': 3 }, alert);
     * // => alerts each number value (order is not guaranteed)
     */
    function forEach(collection, callback, thisArg) {
      if (callback && typeof thisArg == 'undefined' && isArray(collection)) {
        var index = -1,
            length = collection.length;

        while (++index < length) {
          if (callback(collection[index], index, collection) === false) {
            break;
          }
        }
      } else {
        each(collection, callback, thisArg);
      }
      return collection;
    }

    /**
     * Creates an object composed of keys returned from running each element of the
     * `collection` through the `callback`. The corresponding value of each key is
     * an array of elements passed to `callback` that returned the key. The `callback`
     * is bound to `thisArg` and invoked with three arguments; (value, index|key, collection).
     *
     * If a property name is passed for `callback`, the created "_.pluck" style
     * callback will return the property value of the given element.
     *
     * If an object is passed for `callback`, the created "_.where" style callback
     * will return `true` for elements that have the properties of the given object,
     * else `false`
     *
     * @static
     * @memberOf _
     * @category Collections
     * @param {Array|Object|String} collection The collection to iterate over.
     * @param {Function|Object|String} [callback=identity] The function called per
     *  iteration. If a property name or object is passed, it will be used to create
     *  a "_.pluck" or "_.where" style callback, respectively.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Object} Returns the composed aggregate object.
     * @example
     *
     * _.groupBy([4.2, 6.1, 6.4], function(num) { return Math.floor(num); });
     * // => { '4': [4.2], '6': [6.1, 6.4] }
     *
     * _.groupBy([4.2, 6.1, 6.4], function(num) { return this.floor(num); }, Math);
     * // => { '4': [4.2], '6': [6.1, 6.4] }
     *
     * // using "_.pluck" callback shorthand
     * _.groupBy(['one', 'two', 'three'], 'length');
     * // => { '3': ['one', 'two'], '5': ['three'] }
     */
    function groupBy(collection, callback, thisArg) {
      var result = {};
      callback = lodash.createCallback(callback, thisArg);

      forEach(collection, function(value, key, collection) {
        key = String(callback(value, key, collection));
        (hasOwnProperty.call(result, key) ? result[key] : result[key] = []).push(value);
      });
      return result;
    }

    /**
     * Invokes the method named by `methodName` on each element in the `collection`,
     * returning an array of the results of each invoked method. Additional arguments
     * will be passed to each invoked method. If `methodName` is a function, it will
     * be invoked for, and `this` bound to, each element in the `collection`.
     *
     * @static
     * @memberOf _
     * @category Collections
     * @param {Array|Object|String} collection The collection to iterate over.
     * @param {Function|String} methodName The name of the method to invoke or
     *  the function invoked per iteration.
     * @param {Mixed} [arg1, arg2, ...] Arguments to invoke the method with.
     * @returns {Array} Returns a new array of the results of each invoked method.
     * @example
     *
     * _.invoke([[5, 1, 7], [3, 2, 1]], 'sort');
     * // => [[1, 5, 7], [1, 2, 3]]
     *
     * _.invoke([123, 456], String.prototype.split, '');
     * // => [['1', '2', '3'], ['4', '5', '6']]
     */
    function invoke(collection, methodName) {
      var args = nativeSlice.call(arguments, 2),
          index = -1,
          isFunc = typeof methodName == 'function',
          length = collection ? collection.length : 0,
          result = Array(typeof length == 'number' ? length : 0);

      forEach(collection, function(value) {
        result[++index] = (isFunc ? methodName : value[methodName]).apply(value, args);
      });
      return result;
    }

    /**
     * Creates an array of values by running each element in the `collection`
     * through the `callback`. The `callback` is bound to `thisArg` and invoked with
     * three arguments; (value, index|key, collection).
     *
     * If a property name is passed for `callback`, the created "_.pluck" style
     * callback will return the property value of the given element.
     *
     * If an object is passed for `callback`, the created "_.where" style callback
     * will return `true` for elements that have the properties of the given object,
     * else `false`.
     *
     * @static
     * @memberOf _
     * @alias collect
     * @category Collections
     * @param {Array|Object|String} collection The collection to iterate over.
     * @param {Function|Object|String} [callback=identity] The function called per
     *  iteration. If a property name or object is passed, it will be used to create
     *  a "_.pluck" or "_.where" style callback, respectively.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Array} Returns a new array of the results of each `callback` execution.
     * @example
     *
     * _.map([1, 2, 3], function(num) { return num * 3; });
     * // => [3, 6, 9]
     *
     * _.map({ 'one': 1, 'two': 2, 'three': 3 }, function(num) { return num * 3; });
     * // => [3, 6, 9] (order is not guaranteed)
     *
     * var stooges = [
     *   { 'name': 'moe', 'age': 40 },
     *   { 'name': 'larry', 'age': 50 }
     * ];
     *
     * // using "_.pluck" callback shorthand
     * _.map(stooges, 'name');
     * // => ['moe', 'larry']
     */
    function map(collection, callback, thisArg) {
      var index = -1,
          length = collection ? collection.length : 0,
          result = Array(typeof length == 'number' ? length : 0);

      callback = lodash.createCallback(callback, thisArg);
      if (isArray(collection)) {
        while (++index < length) {
          result[index] = callback(collection[index], index, collection);
        }
      } else {
        each(collection, function(value, key, collection) {
          result[++index] = callback(value, key, collection);
        });
      }
      return result;
    }

    /**
     * Retrieves the maximum value of an `array`. If `callback` is passed,
     * it will be executed for each value in the `array` to generate the
     * criterion by which the value is ranked. The `callback` is bound to
     * `thisArg` and invoked with three arguments; (value, index, collection).
     *
     * If a property name is passed for `callback`, the created "_.pluck" style
     * callback will return the property value of the given element.
     *
     * If an object is passed for `callback`, the created "_.where" style callback
     * will return `true` for elements that have the properties of the given object,
     * else `false`.
     *
     * @static
     * @memberOf _
     * @category Collections
     * @param {Array|Object|String} collection The collection to iterate over.
     * @param {Function|Object|String} [callback=identity] The function called per
     *  iteration. If a property name or object is passed, it will be used to create
     *  a "_.pluck" or "_.where" style callback, respectively.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Mixed} Returns the maximum value.
     * @example
     *
     * _.max([4, 2, 8, 6]);
     * // => 8
     *
     * var stooges = [
     *   { 'name': 'moe', 'age': 40 },
     *   { 'name': 'larry', 'age': 50 }
     * ];
     *
     * _.max(stooges, function(stooge) { return stooge.age; });
     * // => { 'name': 'larry', 'age': 50 };
     *
     * // using "_.pluck" callback shorthand
     * _.max(stooges, 'age');
     * // => { 'name': 'larry', 'age': 50 };
     */
    function max(collection, callback, thisArg) {
      var computed = -Infinity,
          result = computed;

      if (!callback && isArray(collection)) {
        var index = -1,
            length = collection.length;

        while (++index < length) {
          var value = collection[index];
          if (value > result) {
            result = value;
          }
        }
      } else {
        callback = (!callback && isString(collection))
          ? charAtCallback
          : lodash.createCallback(callback, thisArg);

        each(collection, function(value, index, collection) {
          var current = callback(value, index, collection);
          if (current > computed) {
            computed = current;
            result = value;
          }
        });
      }
      return result;
    }

    /**
     * Retrieves the minimum value of an `array`. If `callback` is passed,
     * it will be executed for each value in the `array` to generate the
     * criterion by which the value is ranked. The `callback` is bound to `thisArg`
     * and invoked with three arguments; (value, index, collection).
     *
     * If a property name is passed for `callback`, the created "_.pluck" style
     * callback will return the property value of the given element.
     *
     * If an object is passed for `callback`, the created "_.where" style callback
     * will return `true` for elements that have the properties of the given object,
     * else `false`.
     *
     * @static
     * @memberOf _
     * @category Collections
     * @param {Array|Object|String} collection The collection to iterate over.
     * @param {Function|Object|String} [callback=identity] The function called per
     *  iteration. If a property name or object is passed, it will be used to create
     *  a "_.pluck" or "_.where" style callback, respectively.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Mixed} Returns the minimum value.
     * @example
     *
     * _.min([4, 2, 8, 6]);
     * // => 2
     *
     * var stooges = [
     *   { 'name': 'moe', 'age': 40 },
     *   { 'name': 'larry', 'age': 50 }
     * ];
     *
     * _.min(stooges, function(stooge) { return stooge.age; });
     * // => { 'name': 'moe', 'age': 40 };
     *
     * // using "_.pluck" callback shorthand
     * _.min(stooges, 'age');
     * // => { 'name': 'moe', 'age': 40 };
     */
    function min(collection, callback, thisArg) {
      var computed = Infinity,
          result = computed;

      if (!callback && isArray(collection)) {
        var index = -1,
            length = collection.length;

        while (++index < length) {
          var value = collection[index];
          if (value < result) {
            result = value;
          }
        }
      } else {
        callback = (!callback && isString(collection))
          ? charAtCallback
          : lodash.createCallback(callback, thisArg);

        each(collection, function(value, index, collection) {
          var current = callback(value, index, collection);
          if (current < computed) {
            computed = current;
            result = value;
          }
        });
      }
      return result;
    }

    /**
     * Retrieves the value of a specified property from all elements in the `collection`.
     *
     * @static
     * @memberOf _
     * @type Function
     * @category Collections
     * @param {Array|Object|String} collection The collection to iterate over.
     * @param {String} property The property to pluck.
     * @returns {Array} Returns a new array of property values.
     * @example
     *
     * var stooges = [
     *   { 'name': 'moe', 'age': 40 },
     *   { 'name': 'larry', 'age': 50 }
     * ];
     *
     * _.pluck(stooges, 'name');
     * // => ['moe', 'larry']
     */
    var pluck = map;

    /**
     * Reduces a `collection` to a value which is the accumulated result of running
     * each element in the `collection` through the `callback`, where each successive
     * `callback` execution consumes the return value of the previous execution.
     * If `accumulator` is not passed, the first element of the `collection` will be
     * used as the initial `accumulator` value. The `callback` is bound to `thisArg`
     * and invoked with four arguments; (accumulator, value, index|key, collection).
     *
     * @static
     * @memberOf _
     * @alias foldl, inject
     * @category Collections
     * @param {Array|Object|String} collection The collection to iterate over.
     * @param {Function} [callback=identity] The function called per iteration.
     * @param {Mixed} [accumulator] Initial value of the accumulator.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Mixed} Returns the accumulated value.
     * @example
     *
     * var sum = _.reduce([1, 2, 3], function(sum, num) {
     *   return sum + num;
     * });
     * // => 6
     *
     * var mapped = _.reduce({ 'a': 1, 'b': 2, 'c': 3 }, function(result, num, key) {
     *   result[key] = num * 3;
     *   return result;
     * }, {});
     * // => { 'a': 3, 'b': 6, 'c': 9 }
     */
    function reduce(collection, callback, accumulator, thisArg) {
      var noaccum = arguments.length < 3;
      callback = lodash.createCallback(callback, thisArg, 4);

      if (isArray(collection)) {
        var index = -1,
            length = collection.length;

        if (noaccum) {
          accumulator = collection[++index];
        }
        while (++index < length) {
          accumulator = callback(accumulator, collection[index], index, collection);
        }
      } else {
        each(collection, function(value, index, collection) {
          accumulator = noaccum
            ? (noaccum = false, value)
            : callback(accumulator, value, index, collection)
        });
      }
      return accumulator;
    }

    /**
     * This method is similar to `_.reduce`, except that it iterates over a
     * `collection` from right to left.
     *
     * @static
     * @memberOf _
     * @alias foldr
     * @category Collections
     * @param {Array|Object|String} collection The collection to iterate over.
     * @param {Function} [callback=identity] The function called per iteration.
     * @param {Mixed} [accumulator] Initial value of the accumulator.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Mixed} Returns the accumulated value.
     * @example
     *
     * var list = [[0, 1], [2, 3], [4, 5]];
     * var flat = _.reduceRight(list, function(a, b) { return a.concat(b); }, []);
     * // => [4, 5, 2, 3, 0, 1]
     */
    function reduceRight(collection, callback, accumulator, thisArg) {
      var iterable = collection,
          length = collection ? collection.length : 0,
          noaccum = arguments.length < 3;

      if (typeof length != 'number') {
        var props = keys(collection);
        length = props.length;
      } else if (support.unindexedChars && isString(collection)) {
        iterable = collection.split('');
      }
      callback = lodash.createCallback(callback, thisArg, 4);
      forEach(collection, function(value, index, collection) {
        index = props ? props[--length] : --length;
        accumulator = noaccum
          ? (noaccum = false, iterable[index])
          : callback(accumulator, iterable[index], index, collection);
      });
      return accumulator;
    }

    /**
     * The opposite of `_.filter`, this method returns the elements of a
     * `collection` that `callback` does **not** return truthy for.
     *
     * If a property name is passed for `callback`, the created "_.pluck" style
     * callback will return the property value of the given element.
     *
     * If an object is passed for `callback`, the created "_.where" style callback
     * will return `true` for elements that have the properties of the given object,
     * else `false`.
     *
     * @static
     * @memberOf _
     * @category Collections
     * @param {Array|Object|String} collection The collection to iterate over.
     * @param {Function|Object|String} [callback=identity] The function called per
     *  iteration. If a property name or object is passed, it will be used to create
     *  a "_.pluck" or "_.where" style callback, respectively.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Array} Returns a new array of elements that did **not** pass the
     *  callback check.
     * @example
     *
     * var odds = _.reject([1, 2, 3, 4, 5, 6], function(num) { return num % 2 == 0; });
     * // => [1, 3, 5]
     *
     * var food = [
     *   { 'name': 'apple',  'organic': false, 'type': 'fruit' },
     *   { 'name': 'carrot', 'organic': true,  'type': 'vegetable' }
     * ];
     *
     * // using "_.pluck" callback shorthand
     * _.reject(food, 'organic');
     * // => [{ 'name': 'apple', 'organic': false, 'type': 'fruit' }]
     *
     * // using "_.where" callback shorthand
     * _.reject(food, { 'type': 'fruit' });
     * // => [{ 'name': 'carrot', 'organic': true, 'type': 'vegetable' }]
     */
    function reject(collection, callback, thisArg) {
      callback = lodash.createCallback(callback, thisArg);
      return filter(collection, function(value, index, collection) {
        return !callback(value, index, collection);
      });
    }

    /**
     * Creates an array of shuffled `array` values, using a version of the
     * Fisher-Yates shuffle. See http://en.wikipedia.org/wiki/Fisher-Yates_shuffle.
     *
     * @static
     * @memberOf _
     * @category Collections
     * @param {Array|Object|String} collection The collection to shuffle.
     * @returns {Array} Returns a new shuffled collection.
     * @example
     *
     * _.shuffle([1, 2, 3, 4, 5, 6]);
     * // => [4, 1, 6, 3, 5, 2]
     */
    function shuffle(collection) {
      var index = -1,
          length = collection ? collection.length : 0,
          result = Array(typeof length == 'number' ? length : 0);

      forEach(collection, function(value) {
        var rand = floor(nativeRandom() * (++index + 1));
        result[index] = result[rand];
        result[rand] = value;
      });
      return result;
    }

    /**
     * Gets the size of the `collection` by returning `collection.length` for arrays
     * and array-like objects or the number of own enumerable properties for objects.
     *
     * @static
     * @memberOf _
     * @category Collections
     * @param {Array|Object|String} collection The collection to inspect.
     * @returns {Number} Returns `collection.length` or number of own enumerable properties.
     * @example
     *
     * _.size([1, 2]);
     * // => 2
     *
     * _.size({ 'one': 1, 'two': 2, 'three': 3 });
     * // => 3
     *
     * _.size('curly');
     * // => 5
     */
    function size(collection) {
      var length = collection ? collection.length : 0;
      return typeof length == 'number' ? length : keys(collection).length;
    }

    /**
     * Checks if the `callback` returns a truthy value for **any** element of a
     * `collection`. The function returns as soon as it finds passing value, and
     * does not iterate over the entire `collection`. The `callback` is bound to
     * `thisArg` and invoked with three arguments; (value, index|key, collection).
     *
     * If a property name is passed for `callback`, the created "_.pluck" style
     * callback will return the property value of the given element.
     *
     * If an object is passed for `callback`, the created "_.where" style callback
     * will return `true` for elements that have the properties of the given object,
     * else `false`.
     *
     * @static
     * @memberOf _
     * @alias any
     * @category Collections
     * @param {Array|Object|String} collection The collection to iterate over.
     * @param {Function|Object|String} [callback=identity] The function called per
     *  iteration. If a property name or object is passed, it will be used to create
     *  a "_.pluck" or "_.where" style callback, respectively.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Boolean} Returns `true` if any element passes the callback check,
     *  else `false`.
     * @example
     *
     * _.some([null, 0, 'yes', false], Boolean);
     * // => true
     *
     * var food = [
     *   { 'name': 'apple',  'organic': false, 'type': 'fruit' },
     *   { 'name': 'carrot', 'organic': true,  'type': 'vegetable' }
     * ];
     *
     * // using "_.pluck" callback shorthand
     * _.some(food, 'organic');
     * // => true
     *
     * // using "_.where" callback shorthand
     * _.some(food, { 'type': 'meat' });
     * // => false
     */
    function some(collection, callback, thisArg) {
      var result;
      callback = lodash.createCallback(callback, thisArg);

      if (isArray(collection)) {
        var index = -1,
            length = collection.length;

        while (++index < length) {
          if ((result = callback(collection[index], index, collection))) {
            break;
          }
        }
      } else {
        each(collection, function(value, index, collection) {
          return !(result = callback(value, index, collection));
        });
      }
      return !!result;
    }

    /**
     * Creates an array of elements, sorted in ascending order by the results of
     * running each element in the `collection` through the `callback`. This method
     * performs a stable sort, that is, it will preserve the original sort order of
     * equal elements. The `callback` is bound to `thisArg` and invoked with three
     * arguments; (value, index|key, collection).
     *
     * If a property name is passed for `callback`, the created "_.pluck" style
     * callback will return the property value of the given element.
     *
     * If an object is passed for `callback`, the created "_.where" style callback
     * will return `true` for elements that have the properties of the given object,
     * else `false`.
     *
     * @static
     * @memberOf _
     * @category Collections
     * @param {Array|Object|String} collection The collection to iterate over.
     * @param {Function|Object|String} [callback=identity] The function called per
     *  iteration. If a property name or object is passed, it will be used to create
     *  a "_.pluck" or "_.where" style callback, respectively.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Array} Returns a new array of sorted elements.
     * @example
     *
     * _.sortBy([1, 2, 3], function(num) { return Math.sin(num); });
     * // => [3, 1, 2]
     *
     * _.sortBy([1, 2, 3], function(num) { return this.sin(num); }, Math);
     * // => [3, 1, 2]
     *
     * // using "_.pluck" callback shorthand
     * _.sortBy(['banana', 'strawberry', 'apple'], 'length');
     * // => ['apple', 'banana', 'strawberry']
     */
    function sortBy(collection, callback, thisArg) {
      var index = -1,
          length = collection ? collection.length : 0,
          result = Array(typeof length == 'number' ? length : 0);

      callback = lodash.createCallback(callback, thisArg);
      forEach(collection, function(value, key, collection) {
        result[++index] = {
          'criteria': callback(value, key, collection),
          'index': index,
          'value': value
        };
      });

      length = result.length;
      result.sort(compareAscending);
      while (length--) {
        result[length] = result[length].value;
      }
      return result;
    }

    /**
     * Converts the `collection` to an array.
     *
     * @static
     * @memberOf _
     * @category Collections
     * @param {Array|Object|String} collection The collection to convert.
     * @returns {Array} Returns the new converted array.
     * @example
     *
     * (function() { return _.toArray(arguments).slice(1); })(1, 2, 3, 4);
     * // => [2, 3, 4]
     */
    function toArray(collection) {
      if (collection && typeof collection.length == 'number') {
        return (support.unindexedChars && isString(collection))
          ? collection.split('')
          : slice(collection);
      }
      return values(collection);
    }

    /**
     * Examines each element in a `collection`, returning an array of all elements
     * that have the given `properties`. When checking `properties`, this method
     * performs a deep comparison between values to determine if they are equivalent
     * to each other.
     *
     * @static
     * @memberOf _
     * @type Function
     * @category Collections
     * @param {Array|Object|String} collection The collection to iterate over.
     * @param {Object} properties The object of property values to filter by.
     * @returns {Array} Returns a new array of elements that have the given `properties`.
     * @example
     *
     * var stooges = [
     *   { 'name': 'moe', 'age': 40 },
     *   { 'name': 'larry', 'age': 50 }
     * ];
     *
     * _.where(stooges, { 'age': 40 });
     * // => [{ 'name': 'moe', 'age': 40 }]
     */
    var where = filter;

    /*--------------------------------------------------------------------------*/

    /**
     * Creates an array with all falsey values of `array` removed. The values
     * `false`, `null`, `0`, `""`, `undefined` and `NaN` are all falsey.
     *
     * @static
     * @memberOf _
     * @category Arrays
     * @param {Array} array The array to compact.
     * @returns {Array} Returns a new filtered array.
     * @example
     *
     * _.compact([0, 1, false, 2, '', 3]);
     * // => [1, 2, 3]
     */
    function compact(array) {
      var index = -1,
          length = array ? array.length : 0,
          result = [];

      while (++index < length) {
        var value = array[index];
        if (value) {
          result.push(value);
        }
      }
      return result;
    }

    /**
     * Creates an array of `array` elements not present in the other arrays
     * using strict equality for comparisons, i.e. `===`.
     *
     * @static
     * @memberOf _
     * @category Arrays
     * @param {Array} array The array to process.
     * @param {Array} [array1, array2, ...] Arrays to check.
     * @returns {Array} Returns a new array of `array` elements not present in the
     *  other arrays.
     * @example
     *
     * _.difference([1, 2, 3, 4, 5], [5, 2, 10]);
     * // => [1, 3, 4]
     */
    function difference(array) {
      var index = -1,
          length = array ? array.length : 0,
          flattened = concat.apply(arrayProto, nativeSlice.call(arguments, 1)),
          contains = cachedContains(flattened),
          result = [];

      while (++index < length) {
        var value = array[index];
        if (!contains(value)) {
          result.push(value);
        }
      }
      return result;
    }

    /**
     * This method is similar to `_.find`, except that it returns the index of
     * the element that passes the callback check, instead of the element itself.
     *
     * @static
     * @memberOf _
     * @category Arrays
     * @param {Array} array The array to search.
     * @param {Function|Object|String} [callback=identity] The function called per
     *  iteration. If a property name or object is passed, it will be used to create
     *  a "_.pluck" or "_.where" style callback, respectively.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Mixed} Returns the index of the found element, else `-1`.
     * @example
     *
     * _.findIndex(['apple', 'banana', 'beet'], function(food) {
     *   return /^b/.test(food);
     * });
     * // => 1
     */
    function findIndex(array, callback, thisArg) {
      var index = -1,
          length = array ? array.length : 0;

      callback = lodash.createCallback(callback, thisArg);
      while (++index < length) {
        if (callback(array[index], index, array)) {
          return index;
        }
      }
      return -1;
    }

    /**
     * Gets the first element of the `array`. If a number `n` is passed, the first
     * `n` elements of the `array` are returned. If a `callback` function is passed,
     * elements at the beginning of the array are returned as long as the `callback`
     * returns truthy. The `callback` is bound to `thisArg` and invoked with three
     * arguments; (value, index, array).
     *
     * If a property name is passed for `callback`, the created "_.pluck" style
     * callback will return the property value of the given element.
     *
     * If an object is passed for `callback`, the created "_.where" style callback
     * will return `true` for elements that have the properties of the given object,
     * else `false`.
     *
     * @static
     * @memberOf _
     * @alias head, take
     * @category Arrays
     * @param {Array} array The array to query.
     * @param {Function|Object|Number|String} [callback|n] The function called
     *  per element or the number of elements to return. If a property name or
     *  object is passed, it will be used to create a "_.pluck" or "_.where"
     *  style callback, respectively.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Mixed} Returns the first element(s) of `array`.
     * @example
     *
     * _.first([1, 2, 3]);
     * // => 1
     *
     * _.first([1, 2, 3], 2);
     * // => [1, 2]
     *
     * _.first([1, 2, 3], function(num) {
     *   return num < 3;
     * });
     * // => [1, 2]
     *
     * var food = [
     *   { 'name': 'banana', 'organic': true },
     *   { 'name': 'beet',   'organic': false },
     * ];
     *
     * // using "_.pluck" callback shorthand
     * _.first(food, 'organic');
     * // => [{ 'name': 'banana', 'organic': true }]
     *
     * var food = [
     *   { 'name': 'apple',  'type': 'fruit' },
     *   { 'name': 'banana', 'type': 'fruit' },
     *   { 'name': 'beet',   'type': 'vegetable' }
     * ];
     *
     * // using "_.where" callback shorthand
     * _.first(food, { 'type': 'fruit' });
     * // => [{ 'name': 'apple', 'type': 'fruit' }, { 'name': 'banana', 'type': 'fruit' }]
     */
    function first(array, callback, thisArg) {
      if (array) {
        var n = 0,
            length = array.length;

        if (typeof callback != 'number' && callback != null) {
          var index = -1;
          callback = lodash.createCallback(callback, thisArg);
          while (++index < length && callback(array[index], index, array)) {
            n++;
          }
        } else {
          n = callback;
          if (n == null || thisArg) {
            return array[0];
          }
        }
        return slice(array, 0, nativeMin(nativeMax(0, n), length));
      }
    }

    /**
     * Flattens a nested array (the nesting can be to any depth). If `isShallow`
     * is truthy, `array` will only be flattened a single level. If `callback`
     * is passed, each element of `array` is passed through a `callback` before
     * flattening. The `callback` is bound to `thisArg` and invoked with three
     * arguments; (value, index, array).
     *
     * If a property name is passed for `callback`, the created "_.pluck" style
     * callback will return the property value of the given element.
     *
     * If an object is passed for `callback`, the created "_.where" style callback
     * will return `true` for elements that have the properties of the given object,
     * else `false`.
     *
     * @static
     * @memberOf _
     * @category Arrays
     * @param {Array} array The array to flatten.
     * @param {Boolean} [isShallow=false] A flag to indicate only flattening a single level.
     * @param {Function|Object|String} [callback=identity] The function called per
     *  iteration. If a property name or object is passed, it will be used to create
     *  a "_.pluck" or "_.where" style callback, respectively.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Array} Returns a new flattened array.
     * @example
     *
     * _.flatten([1, [2], [3, [[4]]]]);
     * // => [1, 2, 3, 4];
     *
     * _.flatten([1, [2], [3, [[4]]]], true);
     * // => [1, 2, 3, [[4]]];
     *
     * var stooges = [
     *   { 'name': 'curly', 'quotes': ['Oh, a wise guy, eh?', 'Poifect!'] },
     *   { 'name': 'moe', 'quotes': ['Spread out!', 'You knucklehead!'] }
     * ];
     *
     * // using "_.pluck" callback shorthand
     * _.flatten(stooges, 'quotes');
     * // => ['Oh, a wise guy, eh?', 'Poifect!', 'Spread out!', 'You knucklehead!']
     */
    function flatten(array, isShallow, callback, thisArg) {
      var index = -1,
          length = array ? array.length : 0,
          result = [];

      // juggle arguments
      if (typeof isShallow != 'boolean' && isShallow != null) {
        thisArg = callback;
        callback = isShallow;
        isShallow = false;
      }
      if (callback != null) {
        callback = lodash.createCallback(callback, thisArg);
      }
      while (++index < length) {
        var value = array[index];
        if (callback) {
          value = callback(value, index, array);
        }
        // recursively flatten arrays (susceptible to call stack limits)
        if (isArray(value)) {
          push.apply(result, isShallow ? value : flatten(value));
        } else {
          result.push(value);
        }
      }
      return result;
    }

    /**
     * Gets the index at which the first occurrence of `value` is found using
     * strict equality for comparisons, i.e. `===`. If the `array` is already
     * sorted, passing `true` for `fromIndex` will run a faster binary search.
     *
     * @static
     * @memberOf _
     * @category Arrays
     * @param {Array} array The array to search.
     * @param {Mixed} value The value to search for.
     * @param {Boolean|Number} [fromIndex=0] The index to search from or `true` to
     *  perform a binary search on a sorted `array`.
     * @returns {Number} Returns the index of the matched value or `-1`.
     * @example
     *
     * _.indexOf([1, 2, 3, 1, 2, 3], 2);
     * // => 1
     *
     * _.indexOf([1, 2, 3, 1, 2, 3], 2, 3);
     * // => 4
     *
     * _.indexOf([1, 1, 2, 2, 3, 3], 2, true);
     * // => 2
     */
    function indexOf(array, value, fromIndex) {
      var index = -1,
          length = array ? array.length : 0;

      if (typeof fromIndex == 'number') {
        index = (fromIndex < 0 ? nativeMax(0, length + fromIndex) : fromIndex || 0) - 1;
      } else if (fromIndex) {
        index = sortedIndex(array, value);
        return array[index] === value ? index : -1;
      }
      while (++index < length) {
        if (array[index] === value) {
          return index;
        }
      }
      return -1;
    }

    /**
     * Gets all but the last element of `array`. If a number `n` is passed, the
     * last `n` elements are excluded from the result. If a `callback` function
     * is passed, elements at the end of the array are excluded from the result
     * as long as the `callback` returns truthy. The `callback` is bound to
     * `thisArg` and invoked with three arguments; (value, index, array).
     *
     * If a property name is passed for `callback`, the created "_.pluck" style
     * callback will return the property value of the given element.
     *
     * If an object is passed for `callback`, the created "_.where" style callback
     * will return `true` for elements that have the properties of the given object,
     * else `false`.
     *
     * @static
     * @memberOf _
     * @category Arrays
     * @param {Array} array The array to query.
     * @param {Function|Object|Number|String} [callback|n=1] The function called
     *  per element or the number of elements to exclude. If a property name or
     *  object is passed, it will be used to create a "_.pluck" or "_.where"
     *  style callback, respectively.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Array} Returns a slice of `array`.
     * @example
     *
     * _.initial([1, 2, 3]);
     * // => [1, 2]
     *
     * _.initial([1, 2, 3], 2);
     * // => [1]
     *
     * _.initial([1, 2, 3], function(num) {
     *   return num > 1;
     * });
     * // => [1]
     *
     * var food = [
     *   { 'name': 'beet',   'organic': false },
     *   { 'name': 'carrot', 'organic': true }
     * ];
     *
     * // using "_.pluck" callback shorthand
     * _.initial(food, 'organic');
     * // => [{ 'name': 'beet',   'organic': false }]
     *
     * var food = [
     *   { 'name': 'banana', 'type': 'fruit' },
     *   { 'name': 'beet',   'type': 'vegetable' },
     *   { 'name': 'carrot', 'type': 'vegetable' }
     * ];
     *
     * // using "_.where" callback shorthand
     * _.initial(food, { 'type': 'vegetable' });
     * // => [{ 'name': 'banana', 'type': 'fruit' }]
     */
    function initial(array, callback, thisArg) {
      if (!array) {
        return [];
      }
      var n = 0,
          length = array.length;

      if (typeof callback != 'number' && callback != null) {
        var index = length;
        callback = lodash.createCallback(callback, thisArg);
        while (index-- && callback(array[index], index, array)) {
          n++;
        }
      } else {
        n = (callback == null || thisArg) ? 1 : callback || n;
      }
      return slice(array, 0, nativeMin(nativeMax(0, length - n), length));
    }

    /**
     * Computes the intersection of all the passed-in arrays using strict equality
     * for comparisons, i.e. `===`.
     *
     * @static
     * @memberOf _
     * @category Arrays
     * @param {Array} [array1, array2, ...] Arrays to process.
     * @returns {Array} Returns a new array of unique elements that are present
     *  in **all** of the arrays.
     * @example
     *
     * _.intersection([1, 2, 3], [101, 2, 1, 10], [2, 1]);
     * // => [1, 2]
     */
    function intersection(array) {
      var args = arguments,
          argsLength = args.length,
          cache = { '0': {} },
          index = -1,
          length = array ? array.length : 0,
          isLarge = length >= largeArraySize,
          result = [],
          seen = result;

      outer:
      while (++index < length) {
        var value = array[index];
        if (isLarge) {
          var key = keyPrefix + value;
          var inited = cache[0][key]
            ? !(seen = cache[0][key])
            : (seen = cache[0][key] = []);
        }
        if (inited || indexOf(seen, value) < 0) {
          if (isLarge) {
            seen.push(value);
          }
          var argsIndex = argsLength;
          while (--argsIndex) {
            if (!(cache[argsIndex] || (cache[argsIndex] = cachedContains(args[argsIndex])))(value)) {
              continue outer;
            }
          }
          result.push(value);
        }
      }
      return result;
    }

    /**
     * Gets the last element of the `array`. If a number `n` is passed, the
     * last `n` elements of the `array` are returned. If a `callback` function
     * is passed, elements at the end of the array are returned as long as the
     * `callback` returns truthy. The `callback` is bound to `thisArg` and
     * invoked with three arguments;(value, index, array).
     *
     *
     * If a property name is passed for `callback`, the created "_.pluck" style
     * callback will return the property value of the given element.
     *
     * If an object is passed for `callback`, the created "_.where" style callback
     * will return `true` for elements that have the properties of the given object,
     * else `false`.
     *
     * @static
     * @memberOf _
     * @category Arrays
     * @param {Array} array The array to query.
     * @param {Function|Object|Number|String} [callback|n] The function called
     *  per element or the number of elements to return. If a property name or
     *  object is passed, it will be used to create a "_.pluck" or "_.where"
     *  style callback, respectively.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Mixed} Returns the last element(s) of `array`.
     * @example
     *
     * _.last([1, 2, 3]);
     * // => 3
     *
     * _.last([1, 2, 3], 2);
     * // => [2, 3]
     *
     * _.last([1, 2, 3], function(num) {
     *   return num > 1;
     * });
     * // => [2, 3]
     *
     * var food = [
     *   { 'name': 'beet',   'organic': false },
     *   { 'name': 'carrot', 'organic': true }
     * ];
     *
     * // using "_.pluck" callback shorthand
     * _.last(food, 'organic');
     * // => [{ 'name': 'carrot', 'organic': true }]
     *
     * var food = [
     *   { 'name': 'banana', 'type': 'fruit' },
     *   { 'name': 'beet',   'type': 'vegetable' },
     *   { 'name': 'carrot', 'type': 'vegetable' }
     * ];
     *
     * // using "_.where" callback shorthand
     * _.last(food, { 'type': 'vegetable' });
     * // => [{ 'name': 'beet', 'type': 'vegetable' }, { 'name': 'carrot', 'type': 'vegetable' }]
     */
    function last(array, callback, thisArg) {
      if (array) {
        var n = 0,
            length = array.length;

        if (typeof callback != 'number' && callback != null) {
          var index = length;
          callback = lodash.createCallback(callback, thisArg);
          while (index-- && callback(array[index], index, array)) {
            n++;
          }
        } else {
          n = callback;
          if (n == null || thisArg) {
            return array[length - 1];
          }
        }
        return slice(array, nativeMax(0, length - n));
      }
    }

    /**
     * Gets the index at which the last occurrence of `value` is found using strict
     * equality for comparisons, i.e. `===`. If `fromIndex` is negative, it is used
     * as the offset from the end of the collection.
     *
     * @static
     * @memberOf _
     * @category Arrays
     * @param {Array} array The array to search.
     * @param {Mixed} value The value to search for.
     * @param {Number} [fromIndex=array.length-1] The index to search from.
     * @returns {Number} Returns the index of the matched value or `-1`.
     * @example
     *
     * _.lastIndexOf([1, 2, 3, 1, 2, 3], 2);
     * // => 4
     *
     * _.lastIndexOf([1, 2, 3, 1, 2, 3], 2, 3);
     * // => 1
     */
    function lastIndexOf(array, value, fromIndex) {
      var index = array ? array.length : 0;
      if (typeof fromIndex == 'number') {
        index = (fromIndex < 0 ? nativeMax(0, index + fromIndex) : nativeMin(fromIndex, index - 1)) + 1;
      }
      while (index--) {
        if (array[index] === value) {
          return index;
        }
      }
      return -1;
    }

    /**
     * Creates an array of numbers (positive and/or negative) progressing from
     * `start` up to but not including `end`.
     *
     * @static
     * @memberOf _
     * @category Arrays
     * @param {Number} [start=0] The start of the range.
     * @param {Number} end The end of the range.
     * @param {Number} [step=1] The value to increment or decrement by.
     * @returns {Array} Returns a new range array.
     * @example
     *
     * _.range(10);
     * // => [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
     *
     * _.range(1, 11);
     * // => [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
     *
     * _.range(0, 30, 5);
     * // => [0, 5, 10, 15, 20, 25]
     *
     * _.range(0, -10, -1);
     * // => [0, -1, -2, -3, -4, -5, -6, -7, -8, -9]
     *
     * _.range(0);
     * // => []
     */
    function range(start, end, step) {
      start = +start || 0;
      step = +step || 1;

      if (end == null) {
        end = start;
        start = 0;
      }
      // use `Array(length)` so V8 will avoid the slower "dictionary" mode
      // http://youtu.be/XAqIpGU8ZZk#t=17m25s
      var index = -1,
          length = nativeMax(0, ceil((end - start) / step)),
          result = Array(length);

      while (++index < length) {
        result[index] = start;
        start += step;
      }
      return result;
    }

    /**
     * The opposite of `_.initial`, this method gets all but the first value of
     * `array`. If a number `n` is passed, the first `n` values are excluded from
     * the result. If a `callback` function is passed, elements at the beginning
     * of the array are excluded from the result as long as the `callback` returns
     * truthy. The `callback` is bound to `thisArg` and invoked with three
     * arguments; (value, index, array).
     *
     * If a property name is passed for `callback`, the created "_.pluck" style
     * callback will return the property value of the given element.
     *
     * If an object is passed for `callback`, the created "_.where" style callback
     * will return `true` for elements that have the properties of the given object,
     * else `false`.
     *
     * @static
     * @memberOf _
     * @alias drop, tail
     * @category Arrays
     * @param {Array} array The array to query.
     * @param {Function|Object|Number|String} [callback|n=1] The function called
     *  per element or the number of elements to exclude. If a property name or
     *  object is passed, it will be used to create a "_.pluck" or "_.where"
     *  style callback, respectively.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Array} Returns a slice of `array`.
     * @example
     *
     * _.rest([1, 2, 3]);
     * // => [2, 3]
     *
     * _.rest([1, 2, 3], 2);
     * // => [3]
     *
     * _.rest([1, 2, 3], function(num) {
     *   return num < 3;
     * });
     * // => [3]
     *
     * var food = [
     *   { 'name': 'banana', 'organic': true },
     *   { 'name': 'beet',   'organic': false },
     * ];
     *
     * // using "_.pluck" callback shorthand
     * _.rest(food, 'organic');
     * // => [{ 'name': 'beet', 'organic': false }]
     *
     * var food = [
     *   { 'name': 'apple',  'type': 'fruit' },
     *   { 'name': 'banana', 'type': 'fruit' },
     *   { 'name': 'beet',   'type': 'vegetable' }
     * ];
     *
     * // using "_.where" callback shorthand
     * _.rest(food, { 'type': 'fruit' });
     * // => [{ 'name': 'beet', 'type': 'vegetable' }]
     */
    function rest(array, callback, thisArg) {
      if (typeof callback != 'number' && callback != null) {
        var n = 0,
            index = -1,
            length = array ? array.length : 0;

        callback = lodash.createCallback(callback, thisArg);
        while (++index < length && callback(array[index], index, array)) {
          n++;
        }
      } else {
        n = (callback == null || thisArg) ? 1 : nativeMax(0, callback);
      }
      return slice(array, n);
    }

    /**
     * Uses a binary search to determine the smallest index at which the `value`
     * should be inserted into `array` in order to maintain the sort order of the
     * sorted `array`. If `callback` is passed, it will be executed for `value` and
     * each element in `array` to compute their sort ranking. The `callback` is
     * bound to `thisArg` and invoked with one argument; (value).
     *
     * If a property name is passed for `callback`, the created "_.pluck" style
     * callback will return the property value of the given element.
     *
     * If an object is passed for `callback`, the created "_.where" style callback
     * will return `true` for elements that have the properties of the given object,
     * else `false`.
     *
     * @static
     * @memberOf _
     * @category Arrays
     * @param {Array} array The array to inspect.
     * @param {Mixed} value The value to evaluate.
     * @param {Function|Object|String} [callback=identity] The function called per
     *  iteration. If a property name or object is passed, it will be used to create
     *  a "_.pluck" or "_.where" style callback, respectively.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Number} Returns the index at which the value should be inserted
     *  into `array`.
     * @example
     *
     * _.sortedIndex([20, 30, 50], 40);
     * // => 2
     *
     * // using "_.pluck" callback shorthand
     * _.sortedIndex([{ 'x': 20 }, { 'x': 30 }, { 'x': 50 }], { 'x': 40 }, 'x');
     * // => 2
     *
     * var dict = {
     *   'wordToNumber': { 'twenty': 20, 'thirty': 30, 'fourty': 40, 'fifty': 50 }
     * };
     *
     * _.sortedIndex(['twenty', 'thirty', 'fifty'], 'fourty', function(word) {
     *   return dict.wordToNumber[word];
     * });
     * // => 2
     *
     * _.sortedIndex(['twenty', 'thirty', 'fifty'], 'fourty', function(word) {
     *   return this.wordToNumber[word];
     * }, dict);
     * // => 2
     */
    function sortedIndex(array, value, callback, thisArg) {
      var low = 0,
          high = array ? array.length : low;

      // explicitly reference `identity` for better inlining in Firefox
      callback = callback ? lodash.createCallback(callback, thisArg, 1) : identity;
      value = callback(value);

      while (low < high) {
        var mid = (low + high) >>> 1;
        (callback(array[mid]) < value)
          ? low = mid + 1
          : high = mid;
      }
      return low;
    }

    /**
     * Computes the union of the passed-in arrays using strict equality for
     * comparisons, i.e. `===`.
     *
     * @static
     * @memberOf _
     * @category Arrays
     * @param {Array} [array1, array2, ...] Arrays to process.
     * @returns {Array} Returns a new array of unique values, in order, that are
     *  present in one or more of the arrays.
     * @example
     *
     * _.union([1, 2, 3], [101, 2, 1, 10], [2, 1]);
     * // => [1, 2, 3, 101, 10]
     */
    function union(array) {
      if (!isArray(array)) {
        arguments[0] = array ? nativeSlice.call(array) : arrayProto;
      }
      return uniq(concat.apply(arrayProto, arguments));
    }

    /**
     * Creates a duplicate-value-free version of the `array` using strict equality
     * for comparisons, i.e. `===`. If the `array` is already sorted, passing `true`
     * for `isSorted` will run a faster algorithm. If `callback` is passed, each
     * element of `array` is passed through a `callback` before uniqueness is computed.
     * The `callback` is bound to `thisArg` and invoked with three arguments; (value, index, array).
     *
     * If a property name is passed for `callback`, the created "_.pluck" style
     * callback will return the property value of the given element.
     *
     * If an object is passed for `callback`, the created "_.where" style callback
     * will return `true` for elements that have the properties of the given object,
     * else `false`.
     *
     * @static
     * @memberOf _
     * @alias unique
     * @category Arrays
     * @param {Array} array The array to process.
     * @param {Boolean} [isSorted=false] A flag to indicate that the `array` is already sorted.
     * @param {Function|Object|String} [callback=identity] The function called per
     *  iteration. If a property name or object is passed, it will be used to create
     *  a "_.pluck" or "_.where" style callback, respectively.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Array} Returns a duplicate-value-free array.
     * @example
     *
     * _.uniq([1, 2, 1, 3, 1]);
     * // => [1, 2, 3]
     *
     * _.uniq([1, 1, 2, 2, 3], true);
     * // => [1, 2, 3]
     *
     * _.uniq([1, 2, 1.5, 3, 2.5], function(num) { return Math.floor(num); });
     * // => [1, 2, 3]
     *
     * _.uniq([1, 2, 1.5, 3, 2.5], function(num) { return this.floor(num); }, Math);
     * // => [1, 2, 3]
     *
     * // using "_.pluck" callback shorthand
     * _.uniq([{ 'x': 1 }, { 'x': 2 }, { 'x': 1 }], 'x');
     * // => [{ 'x': 1 }, { 'x': 2 }]
     */
    function uniq(array, isSorted, callback, thisArg) {
      var index = -1,
          length = array ? array.length : 0,
          result = [],
          seen = result;

      // juggle arguments
      if (typeof isSorted != 'boolean' && isSorted != null) {
        thisArg = callback;
        callback = isSorted;
        isSorted = false;
      }
      // init value cache for large arrays
      var isLarge = !isSorted && length >= largeArraySize;
      if (isLarge) {
        var cache = {};
      }
      if (callback != null) {
        seen = [];
        callback = lodash.createCallback(callback, thisArg);
      }
      while (++index < length) {
        var value = array[index],
            computed = callback ? callback(value, index, array) : value;

        if (isLarge) {
          var key = keyPrefix + computed;
          var inited = cache[key]
            ? !(seen = cache[key])
            : (seen = cache[key] = []);
        }
        if (isSorted
              ? !index || seen[seen.length - 1] !== computed
              : inited || indexOf(seen, computed) < 0
            ) {
          if (callback || isLarge) {
            seen.push(computed);
          }
          result.push(value);
        }
      }
      return result;
    }

    /**
     * The inverse of `_.zip`, this method splits groups of elements into arrays
     * composed of elements from each group at their corresponding indexes.
     *
     * @static
     * @memberOf _
     * @category Arrays
     * @param {Array} array The array to process.
     * @returns {Array} Returns a new array of the composed arrays.
     * @example
     *
     * _.unzip([['moe', 30, true], ['larry', 40, false]]);
     * // => [['moe', 'larry'], [30, 40], [true, false]];
     */
    function unzip(array) {
      var index = -1,
          length = array ? max(pluck(array, 'length')) : 0,
          result = Array(length < 0 ? 0 : length);

      while (++index < length) {
        result[index] = pluck(array, index);
      }
      return result;
    }

    /**
     * Creates an array with all occurrences of the passed values removed using
     * strict equality for comparisons, i.e. `===`.
     *
     * @static
     * @memberOf _
     * @category Arrays
     * @param {Array} array The array to filter.
     * @param {Mixed} [value1, value2, ...] Values to remove.
     * @returns {Array} Returns a new filtered array.
     * @example
     *
     * _.without([1, 2, 1, 0, 3, 1, 4], 0, 1);
     * // => [2, 3, 4]
     */
    function without(array) {
      return difference(array, nativeSlice.call(arguments, 1));
    }

    /**
     * Groups the elements of each array at their corresponding indexes. Useful for
     * separate data sources that are coordinated through matching array indexes.
     * For a matrix of nested arrays, `_.zip.apply(...)` can transpose the matrix
     * in a similar fashion.
     *
     * @static
     * @memberOf _
     * @category Arrays
     * @param {Array} [array1, array2, ...] Arrays to process.
     * @returns {Array} Returns a new array of grouped elements.
     * @example
     *
     * _.zip(['moe', 'larry'], [30, 40], [true, false]);
     * // => [['moe', 30, true], ['larry', 40, false]]
     */
    function zip(array) {
      return array ? unzip(arguments) : [];
    }

    /**
     * Creates an object composed from arrays of `keys` and `values`. Pass either
     * a single two dimensional array, i.e. `[[key1, value1], [key2, value2]]`, or
     * two arrays, one of `keys` and one of corresponding `values`.
     *
     * @static
     * @memberOf _
     * @alias object
     * @category Arrays
     * @param {Array} keys The array of keys.
     * @param {Array} [values=[]] The array of values.
     * @returns {Object} Returns an object composed of the given keys and
     *  corresponding values.
     * @example
     *
     * _.zipObject(['moe', 'larry'], [30, 40]);
     * // => { 'moe': 30, 'larry': 40 }
     */
    function zipObject(keys, values) {
      var index = -1,
          length = keys ? keys.length : 0,
          result = {};

      while (++index < length) {
        var key = keys[index];
        if (values) {
          result[key] = values[index];
        } else {
          result[key[0]] = key[1];
        }
      }
      return result;
    }

    /*--------------------------------------------------------------------------*/

    /**
     * If `n` is greater than `0`, a function is created that is restricted to
     * executing `func`, with the `this` binding and arguments of the created
     * function, only after it is called `n` times. If `n` is less than `1`,
     * `func` is executed immediately, without a `this` binding or additional
     * arguments, and its result is returned.
     *
     * @static
     * @memberOf _
     * @category Functions
     * @param {Number} n The number of times the function must be called before
     * it is executed.
     * @param {Function} func The function to restrict.
     * @returns {Function} Returns the new restricted function.
     * @example
     *
     * var renderNotes = _.after(notes.length, render);
     * _.forEach(notes, function(note) {
     *   note.asyncSave({ 'success': renderNotes });
     * });
     * // `renderNotes` is run once, after all notes have saved
     */
    function after(n, func) {
      if (n < 1) {
        return func();
      }
      return function() {
        if (--n < 1) {
          return func.apply(this, arguments);
        }
      };
    }

    /**
     * Creates a function that, when called, invokes `func` with the `this`
     * binding of `thisArg` and prepends any additional `bind` arguments to those
     * passed to the bound function.
     *
     * @static
     * @memberOf _
     * @category Functions
     * @param {Function} func The function to bind.
     * @param {Mixed} [thisArg] The `this` binding of `func`.
     * @param {Mixed} [arg1, arg2, ...] Arguments to be partially applied.
     * @returns {Function} Returns the new bound function.
     * @example
     *
     * var func = function(greeting) {
     *   return greeting + ' ' + this.name;
     * };
     *
     * func = _.bind(func, { 'name': 'moe' }, 'hi');
     * func();
     * // => 'hi moe'
     */
    function bind(func, thisArg) {
      // use `Function#bind` if it exists and is fast
      // (in V8 `Function#bind` is slower except when partially applied)
      return support.fastBind || (nativeBind && arguments.length > 2)
        ? nativeBind.call.apply(nativeBind, arguments)
        : createBound(func, thisArg, nativeSlice.call(arguments, 2));
    }

    /**
     * Binds methods on `object` to `object`, overwriting the existing method.
     * Method names may be specified as individual arguments or as arrays of method
     * names. If no method names are provided, all the function properties of `object`
     * will be bound.
     *
     * @static
     * @memberOf _
     * @category Functions
     * @param {Object} object The object to bind and assign the bound methods to.
     * @param {String} [methodName1, methodName2, ...] Method names on the object to bind.
     * @returns {Object} Returns `object`.
     * @example
     *
     * var view = {
     *  'label': 'docs',
     *  'onClick': function() { alert('clicked ' + this.label); }
     * };
     *
     * _.bindAll(view);
     * jQuery('#docs').on('click', view.onClick);
     * // => alerts 'clicked docs', when the button is clicked
     */
    function bindAll(object) {
      var funcs = arguments.length > 1 ? concat.apply(arrayProto, nativeSlice.call(arguments, 1)) : functions(object),
          index = -1,
          length = funcs.length;

      while (++index < length) {
        var key = funcs[index];
        object[key] = bind(object[key], object);
      }
      return object;
    }

    /**
     * Creates a function that, when called, invokes the method at `object[key]`
     * and prepends any additional `bindKey` arguments to those passed to the bound
     * function. This method differs from `_.bind` by allowing bound functions to
     * reference methods that will be redefined or don't yet exist.
     * See http://michaux.ca/articles/lazy-function-definition-pattern.
     *
     * @static
     * @memberOf _
     * @category Functions
     * @param {Object} object The object the method belongs to.
     * @param {String} key The key of the method.
     * @param {Mixed} [arg1, arg2, ...] Arguments to be partially applied.
     * @returns {Function} Returns the new bound function.
     * @example
     *
     * var object = {
     *   'name': 'moe',
     *   'greet': function(greeting) {
     *     return greeting + ' ' + this.name;
     *   }
     * };
     *
     * var func = _.bindKey(object, 'greet', 'hi');
     * func();
     * // => 'hi moe'
     *
     * object.greet = function(greeting) {
     *   return greeting + ', ' + this.name + '!';
     * };
     *
     * func();
     * // => 'hi, moe!'
     */
    function bindKey(object, key) {
      return createBound(object, key, nativeSlice.call(arguments, 2), indicatorObject);
    }

    /**
     * Creates a function that is the composition of the passed functions,
     * where each function consumes the return value of the function that follows.
     * For example, composing the functions `f()`, `g()`, and `h()` produces `f(g(h()))`.
     * Each function is executed with the `this` binding of the composed function.
     *
     * @static
     * @memberOf _
     * @category Functions
     * @param {Function} [func1, func2, ...] Functions to compose.
     * @returns {Function} Returns the new composed function.
     * @example
     *
     * var greet = function(name) { return 'hi ' + name; };
     * var exclaim = function(statement) { return statement + '!'; };
     * var welcome = _.compose(exclaim, greet);
     * welcome('moe');
     * // => 'hi moe!'
     */
    function compose() {
      var funcs = arguments;
      return function() {
        var args = arguments,
            length = funcs.length;

        while (length--) {
          args = [funcs[length].apply(this, args)];
        }
        return args[0];
      };
    }

    /**
     * Produces a callback bound to an optional `thisArg`. If `func` is a property
     * name, the created callback will return the property value for a given element.
     * If `func` is an object, the created callback will return `true` for elements
     * that contain the equivalent object properties, otherwise it will return `false`.
     *
     * Note: All Lo-Dash methods, that accept a `callback` argument, use `_.createCallback`.
     *
     * @static
     * @memberOf _
     * @category Functions
     * @param {Mixed} [func=identity] The value to convert to a callback.
     * @param {Mixed} [thisArg] The `this` binding of the created callback.
     * @param {Number} [argCount=3] The number of arguments the callback accepts.
     * @returns {Function} Returns a callback function.
     * @example
     *
     * var stooges = [
     *   { 'name': 'moe', 'age': 40 },
     *   { 'name': 'larry', 'age': 50 }
     * ];
     *
     * // wrap to create custom callback shorthands
     * _.createCallback = _.wrap(_.createCallback, function(func, callback, thisArg) {
     *   var match = /^(.+?)__([gl]t)(.+)$/.exec(callback);
     *   return !match ? func(callback, thisArg) : function(object) {
     *     return match[2] == 'gt' ? object[match[1]] > match[3] : object[match[1]] < match[3];
     *   };
     * });
     *
     * _.filter(stooges, 'age__gt45');
     * // => [{ 'name': 'larry', 'age': 50 }]
     *
     * // create mixins with support for "_.pluck" and "_.where" callback shorthands
     * _.mixin({
     *   'toLookup': function(collection, callback, thisArg) {
     *     callback = _.createCallback(callback, thisArg);
     *     return _.reduce(collection, function(result, value, index, collection) {
     *       return (result[callback(value, index, collection)] = value, result);
     *     }, {});
     *   }
     * });
     *
     * _.toLookup(stooges, 'name');
     * // => { 'moe': { 'name': 'moe', 'age': 40 }, 'larry': { 'name': 'larry', 'age': 50 } }
     */
    function createCallback(func, thisArg, argCount) {
      if (func == null) {
        return identity;
      }
      var type = typeof func;
      if (type != 'function') {
        if (type != 'object') {
          return function(object) {
            return object[func];
          };
        }
        var props = keys(func);
        return function(object) {
          var length = props.length,
              result = false;
          while (length--) {
            if (!(result = isEqual(object[props[length]], func[props[length]], indicatorObject))) {
              break;
            }
          }
          return result;
        };
      }
      if (typeof thisArg != 'undefined') {
        if (argCount === 1) {
          return function(value) {
            return func.call(thisArg, value);
          };
        }
        if (argCount === 2) {
          return function(a, b) {
            return func.call(thisArg, a, b);
          };
        }
        if (argCount === 4) {
          return function(accumulator, value, index, collection) {
            return func.call(thisArg, accumulator, value, index, collection);
          };
        }
        return function(value, index, collection) {
          return func.call(thisArg, value, index, collection);
        };
      }
      return func;
    }

    /**
     * Creates a function that will delay the execution of `func` until after
     * `wait` milliseconds have elapsed since the last time it was invoked. Pass
     * an `options` object to indicate that `func` should be invoked on the leading
     * and/or trailing edge of the `wait` timeout. Subsequent calls to the debounced
     * function will return the result of the last `func` call.
     *
     * Note: If `leading` and `trailing` options are `true`, `func` will be called
     * on the trailing edge of the timeout only if the the debounced function is
     * invoked more than once during the `wait` timeout.
     *
     * @static
     * @memberOf _
     * @category Functions
     * @param {Function} func The function to debounce.
     * @param {Number} wait The number of milliseconds to delay.
     * @param {Object} options The options object.
     *  [leading=false] A boolean to specify execution on the leading edge of the timeout.
     *  [trailing=true] A boolean to specify execution on the trailing edge of the timeout.
     * @returns {Function} Returns the new debounced function.
     * @example
     *
     * var lazyLayout = _.debounce(calculateLayout, 300);
     * jQuery(window).on('resize', lazyLayout);
     *
     * jQuery('#postbox').on('click', _.debounce(sendMail, 200, {
     *   'leading': true,
     *   'trailing': false
     * });
     */
    function debounce(func, wait, options) {
      var args,
          result,
          thisArg,
          timeoutId,
          callCount = 0,
          trailing = true;

      function delayed() {
        var isCalled = trailing && (!leading || callCount > 1);
        callCount = timeoutId = 0;
        if (isCalled) {
          result = func.apply(thisArg, args);
        }
      }
      if (options === true) {
        var leading = true;
        trailing = false;
      } else if (options && objectTypes[typeof options]) {
        leading = options.leading;
        trailing = 'trailing' in options ? options.trailing : trailing;
      }
      return function() {
        args = arguments;
        thisArg = this;
        clearTimeout(timeoutId);

        if (leading && ++callCount < 2) {
          result = func.apply(thisArg, args);
        }
        timeoutId = setTimeout(delayed, wait);
        return result;
      };
    }

    /**
     * Defers executing the `func` function until the current call stack has cleared.
     * Additional arguments will be passed to `func` when it is invoked.
     *
     * @static
     * @memberOf _
     * @category Functions
     * @param {Function} func The function to defer.
     * @param {Mixed} [arg1, arg2, ...] Arguments to invoke the function with.
     * @returns {Number} Returns the timer id.
     * @example
     *
     * _.defer(function() { alert('deferred'); });
     * // returns from the function before `alert` is called
     */
    function defer(func) {
      var args = nativeSlice.call(arguments, 1);
      return setTimeout(function() { func.apply(undefined, args); }, 1);
    }
    // use `setImmediate` if it's available in Node.js
    if (isV8 && freeModule && typeof setImmediate == 'function') {
      defer = bind(setImmediate, context);
    }

    /**
     * Executes the `func` function after `wait` milliseconds. Additional arguments
     * will be passed to `func` when it is invoked.
     *
     * @static
     * @memberOf _
     * @category Functions
     * @param {Function} func The function to delay.
     * @param {Number} wait The number of milliseconds to delay execution.
     * @param {Mixed} [arg1, arg2, ...] Arguments to invoke the function with.
     * @returns {Number} Returns the timer id.
     * @example
     *
     * var log = _.bind(console.log, console);
     * _.delay(log, 1000, 'logged later');
     * // => 'logged later' (Appears after one second.)
     */
    function delay(func, wait) {
      var args = nativeSlice.call(arguments, 2);
      return setTimeout(function() { func.apply(undefined, args); }, wait);
    }

    /**
     * Creates a function that memoizes the result of `func`. If `resolver` is
     * passed, it will be used to determine the cache key for storing the result
     * based on the arguments passed to the memoized function. By default, the first
     * argument passed to the memoized function is used as the cache key. The `func`
     * is executed with the `this` binding of the memoized function.
     *
     * @static
     * @memberOf _
     * @category Functions
     * @param {Function} func The function to have its output memoized.
     * @param {Function} [resolver] A function used to resolve the cache key.
     * @returns {Function} Returns the new memoizing function.
     * @example
     *
     * var fibonacci = _.memoize(function(n) {
     *   return n < 2 ? n : fibonacci(n - 1) + fibonacci(n - 2);
     * });
     */
    function memoize(func, resolver) {
      function memoized() {
        var cache = memoized.cache,
            key = keyPrefix + (resolver ? resolver.apply(this, arguments) : arguments[0]);

        return hasOwnProperty.call(cache, key)
          ? cache[key]
          : (cache[key] = func.apply(this, arguments));
      }
      memoized.cache = {};
      return memoized;
    }

    /**
     * Creates a function that is restricted to execute `func` once. Repeat calls to
     * the function will return the value of the first call. The `func` is executed
     * with the `this` binding of the created function.
     *
     * @static
     * @memberOf _
     * @category Functions
     * @param {Function} func The function to restrict.
     * @returns {Function} Returns the new restricted function.
     * @example
     *
     * var initialize = _.once(createApplication);
     * initialize();
     * initialize();
     * // `initialize` executes `createApplication` once
     */
    function once(func) {
      var ran,
          result;

      return function() {
        if (ran) {
          return result;
        }
        ran = true;
        result = func.apply(this, arguments);

        // clear the `func` variable so the function may be garbage collected
        func = null;
        return result;
      };
    }

    /**
     * Creates a function that, when called, invokes `func` with any additional
     * `partial` arguments prepended to those passed to the new function. This
     * method is similar to `_.bind`, except it does **not** alter the `this` binding.
     *
     * @static
     * @memberOf _
     * @category Functions
     * @param {Function} func The function to partially apply arguments to.
     * @param {Mixed} [arg1, arg2, ...] Arguments to be partially applied.
     * @returns {Function} Returns the new partially applied function.
     * @example
     *
     * var greet = function(greeting, name) { return greeting + ' ' + name; };
     * var hi = _.partial(greet, 'hi');
     * hi('moe');
     * // => 'hi moe'
     */
    function partial(func) {
      return createBound(func, nativeSlice.call(arguments, 1));
    }

    /**
     * This method is similar to `_.partial`, except that `partial` arguments are
     * appended to those passed to the new function.
     *
     * @static
     * @memberOf _
     * @category Functions
     * @param {Function} func The function to partially apply arguments to.
     * @param {Mixed} [arg1, arg2, ...] Arguments to be partially applied.
     * @returns {Function} Returns the new partially applied function.
     * @example
     *
     * var defaultsDeep = _.partialRight(_.merge, _.defaults);
     *
     * var options = {
     *   'variable': 'data',
     *   'imports': { 'jq': $ }
     * };
     *
     * defaultsDeep(options, _.templateSettings);
     *
     * options.variable
     * // => 'data'
     *
     * options.imports
     * // => { '_': _, 'jq': $ }
     */
    function partialRight(func) {
      return createBound(func, nativeSlice.call(arguments, 1), null, indicatorObject);
    }

    /**
     * Creates a function that, when executed, will only call the `func` function
     * at most once per every `wait` milliseconds. Pass an `options` object to
     * indicate that `func` should be invoked on the leading and/or trailing edge
     * of the `wait` timeout. Subsequent calls to the throttled function will
     * return the result of the last `func` call.
     *
     * Note: If `leading` and `trailing` options are `true`, `func` will be called
     * on the trailing edge of the timeout only if the the throttled function is
     * invoked more than once during the `wait` timeout.
     *
     * @static
     * @memberOf _
     * @category Functions
     * @param {Function} func The function to throttle.
     * @param {Number} wait The number of milliseconds to throttle executions to.
     * @param {Object} options The options object.
     *  [leading=true] A boolean to specify execution on the leading edge of the timeout.
     *  [trailing=true] A boolean to specify execution on the trailing edge of the timeout.
     * @returns {Function} Returns the new throttled function.
     * @example
     *
     * var throttled = _.throttle(updatePosition, 100);
     * jQuery(window).on('scroll', throttled);
     *
     * jQuery('.interactive').on('click', _.throttle(renewToken, 300000, {
     *   'trailing': false
     * }));
     */
    function throttle(func, wait, options) {
      var args,
          result,
          thisArg,
          timeoutId,
          lastCalled = 0,
          leading = true,
          trailing = true;

      function trailingCall() {
        timeoutId = null;
        if (trailing) {
          lastCalled = new Date;
          result = func.apply(thisArg, args);
        }
      }
      if (options === false) {
        leading = false;
      } else if (options && objectTypes[typeof options]) {
        leading = 'leading' in options ? options.leading : leading;
        trailing = 'trailing' in options ? options.trailing : trailing;
      }
      return function() {
        var now = new Date;
        if (!timeoutId && !leading) {
          lastCalled = now;
        }
        var remaining = wait - (now - lastCalled);
        args = arguments;
        thisArg = this;

        if (remaining <= 0) {
          clearTimeout(timeoutId);
          timeoutId = null;
          lastCalled = now;
          result = func.apply(thisArg, args);
        }
        else if (!timeoutId) {
          timeoutId = setTimeout(trailingCall, remaining);
        }
        return result;
      };
    }

    /**
     * Creates a function that passes `value` to the `wrapper` function as its
     * first argument. Additional arguments passed to the function are appended
     * to those passed to the `wrapper` function. The `wrapper` is executed with
     * the `this` binding of the created function.
     *
     * @static
     * @memberOf _
     * @category Functions
     * @param {Mixed} value The value to wrap.
     * @param {Function} wrapper The wrapper function.
     * @returns {Function} Returns the new function.
     * @example
     *
     * var hello = function(name) { return 'hello ' + name; };
     * hello = _.wrap(hello, function(func) {
     *   return 'before, ' + func('moe') + ', after';
     * });
     * hello();
     * // => 'before, hello moe, after'
     */
    function wrap(value, wrapper) {
      return function() {
        var args = [value];
        push.apply(args, arguments);
        return wrapper.apply(this, args);
      };
    }

    /*--------------------------------------------------------------------------*/

    /**
     * Converts the characters `&`, `<`, `>`, `"`, and `'` in `string` to their
     * corresponding HTML entities.
     *
     * @static
     * @memberOf _
     * @category Utilities
     * @param {String} string The string to escape.
     * @returns {String} Returns the escaped string.
     * @example
     *
     * _.escape('Moe, Larry & Curly');
     * // => 'Moe, Larry &amp; Curly'
     */
    function escape(string) {
      return string == null ? '' : String(string).replace(reUnescapedHtml, escapeHtmlChar);
    }

    /**
     * This function returns the first argument passed to it.
     *
     * @static
     * @memberOf _
     * @category Utilities
     * @param {Mixed} value Any value.
     * @returns {Mixed} Returns `value`.
     * @example
     *
     * var moe = { 'name': 'moe' };
     * moe === _.identity(moe);
     * // => true
     */
    function identity(value) {
      return value;
    }

    /**
     * Adds functions properties of `object` to the `lodash` function and chainable
     * wrapper.
     *
     * @static
     * @memberOf _
     * @category Utilities
     * @param {Object} object The object of function properties to add to `lodash`.
     * @example
     *
     * _.mixin({
     *   'capitalize': function(string) {
     *     return string.charAt(0).toUpperCase() + string.slice(1).toLowerCase();
     *   }
     * });
     *
     * _.capitalize('moe');
     * // => 'Moe'
     *
     * _('moe').capitalize();
     * // => 'Moe'
     */
    function mixin(object) {
      forEach(functions(object), function(methodName) {
        var func = lodash[methodName] = object[methodName];

        lodash.prototype[methodName] = function() {
          var value = this.__wrapped__,
              args = [value];

          push.apply(args, arguments);
          var result = func.apply(lodash, args);
          return (value && typeof value == 'object' && value == result)
            ? this
            : new lodashWrapper(result);
        };
      });
    }

    /**
     * Reverts the '_' variable to its previous value and returns a reference to
     * the `lodash` function.
     *
     * @static
     * @memberOf _
     * @category Utilities
     * @returns {Function} Returns the `lodash` function.
     * @example
     *
     * var lodash = _.noConflict();
     */
    function noConflict() {
      context._ = oldDash;
      return this;
    }

    /**
     * Converts the given `value` into an integer of the specified `radix`.
     * If `radix` is `undefined` or `0`, a `radix` of `10` is used unless the
     * `value` is a hexadecimal, in which case a `radix` of `16` is used.
     *
     * Note: This method avoids differences in native ES3 and ES5 `parseInt`
     * implementations. See http://es5.github.com/#E.
     *
     * @static
     * @memberOf _
     * @category Utilities
     * @param {String} value The value to parse.
     * @param {Number} [radix] The radix used to interpret the value to parse.
     * @returns {Number} Returns the new integer value.
     * @example
     *
     * _.parseInt('08');
     * // => 8
     */
    var parseInt = nativeParseInt(whitespace + '08') == 8 ? nativeParseInt : function(value, radix) {
      // Firefox and Opera still follow the ES3 specified implementation of `parseInt`
      return nativeParseInt(isString(value) ? value.replace(reLeadingSpacesAndZeros, '') : value, radix || 0);
    };

    /**
     * Produces a random number between `min` and `max` (inclusive). If only one
     * argument is passed, a number between `0` and the given number will be returned.
     *
     * @static
     * @memberOf _
     * @category Utilities
     * @param {Number} [min=0] The minimum possible value.
     * @param {Number} [max=1] The maximum possible value.
     * @returns {Number} Returns a random number.
     * @example
     *
     * _.random(0, 5);
     * // => a number between 0 and 5
     *
     * _.random(5);
     * // => also a number between 0 and 5
     */
    function random(min, max) {
      if (min == null && max == null) {
        max = 1;
      }
      min = +min || 0;
      if (max == null) {
        max = min;
        min = 0;
      }
      return min + floor(nativeRandom() * ((+max || 0) - min + 1));
    }

    /**
     * Resolves the value of `property` on `object`. If `property` is a function,
     * it will be invoked with the `this` binding of `object` and its result returned,
     * else the property value is returned. If `object` is falsey, then `undefined`
     * is returned.
     *
     * @static
     * @memberOf _
     * @category Utilities
     * @param {Object} object The object to inspect.
     * @param {String} property The property to get the value of.
     * @returns {Mixed} Returns the resolved value.
     * @example
     *
     * var object = {
     *   'cheese': 'crumpets',
     *   'stuff': function() {
     *     return 'nonsense';
     *   }
     * };
     *
     * _.result(object, 'cheese');
     * // => 'crumpets'
     *
     * _.result(object, 'stuff');
     * // => 'nonsense'
     */
    function result(object, property) {
      var value = object ? object[property] : undefined;
      return isFunction(value) ? object[property]() : value;
    }

    /**
     * A micro-templating method that handles arbitrary delimiters, preserves
     * whitespace, and correctly escapes quotes within interpolated code.
     *
     * Note: In the development build, `_.template` utilizes sourceURLs for easier
     * debugging. See http://www.html5rocks.com/en/tutorials/developertools/sourcemaps/#toc-sourceurl
     *
     * For more information on precompiling templates see:
     * http://lodash.com/#custom-builds
     *
     * For more information on Chrome extension sandboxes see:
     * http://developer.chrome.com/stable/extensions/sandboxingEval.html
     *
     * @static
     * @memberOf _
     * @category Utilities
     * @param {String} text The template text.
     * @param {Object} data The data object used to populate the text.
     * @param {Object} options The options object.
     *  escape - The "escape" delimiter regexp.
     *  evaluate - The "evaluate" delimiter regexp.
     *  interpolate - The "interpolate" delimiter regexp.
     *  sourceURL - The sourceURL of the template's compiled source.
     *  variable - The data object variable name.
     * @returns {Function|String} Returns a compiled function when no `data` object
     *  is given, else it returns the interpolated text.
     * @example
     *
     * // using a compiled template
     * var compiled = _.template('hello <%= name %>');
     * compiled({ 'name': 'moe' });
     * // => 'hello moe'
     *
     * var list = '<% _.forEach(people, function(name) { %><li><%= name %></li><% }); %>';
     * _.template(list, { 'people': ['moe', 'larry'] });
     * // => '<li>moe</li><li>larry</li>'
     *
     * // using the "escape" delimiter to escape HTML in data property values
     * _.template('<b><%- value %></b>', { 'value': '<script>' });
     * // => '<b>&lt;script&gt;</b>'
     *
     * // using the ES6 delimiter as an alternative to the default "interpolate" delimiter
     * _.template('hello ${ name }', { 'name': 'curly' });
     * // => 'hello curly'
     *
     * // using the internal `print` function in "evaluate" delimiters
     * _.template('<% print("hello " + epithet); %>!', { 'epithet': 'stooge' });
     * // => 'hello stooge!'
     *
     * // using custom template delimiters
     * _.templateSettings = {
     *   'interpolate': /{{([\s\S]+?)}}/g
     * };
     *
     * _.template('hello {{ name }}!', { 'name': 'mustache' });
     * // => 'hello mustache!'
     *
     * // using the `sourceURL` option to specify a custom sourceURL for the template
     * var compiled = _.template('hello <%= name %>', null, { 'sourceURL': '/basic/greeting.jst' });
     * compiled(data);
     * // => find the source of "greeting.jst" under the Sources tab or Resources panel of the web inspector
     *
     * // using the `variable` option to ensure a with-statement isn't used in the compiled template
     * var compiled = _.template('hi <%= data.name %>!', null, { 'variable': 'data' });
     * compiled.source;
     * // => function(data) {
     *   var __t, __p = '', __e = _.escape;
     *   __p += 'hi ' + ((__t = ( data.name )) == null ? '' : __t) + '!';
     *   return __p;
     * }
     *
     * // using the `source` property to inline compiled templates for meaningful
     * // line numbers in error messages and a stack trace
     * fs.writeFileSync(path.join(cwd, 'jst.js'), '\
     *   var JST = {\
     *     "main": ' + _.template(mainText).source + '\
     *   };\
     * ');
     */
    function template(text, data, options) {
      // based on John Resig's `tmpl` implementation
      // http://ejohn.org/blog/javascript-micro-templating/
      // and Laura Doktorova's doT.js
      // https://github.com/olado/doT
      var settings = lodash.templateSettings;
      text || (text = '');

      // avoid missing dependencies when `iteratorTemplate` is not defined
      options = iteratorTemplate ? defaults({}, options, settings) : settings;

      var imports = iteratorTemplate && defaults({}, options.imports, settings.imports),
          importsKeys = iteratorTemplate ? keys(imports) : ['_'],
          importsValues = iteratorTemplate ? values(imports) : [lodash];

      var isEvaluating,
          index = 0,
          interpolate = options.interpolate || reNoMatch,
          source = "__p += '";

      // compile the regexp to match each delimiter
      var reDelimiters = RegExp(
        (options.escape || reNoMatch).source + '|' +
        interpolate.source + '|' +
        (interpolate === reInterpolate ? reEsTemplate : reNoMatch).source + '|' +
        (options.evaluate || reNoMatch).source + '|$'
      , 'g');

      text.replace(reDelimiters, function(match, escapeValue, interpolateValue, esTemplateValue, evaluateValue, offset) {
        interpolateValue || (interpolateValue = esTemplateValue);

        // escape characters that cannot be included in string literals
        source += text.slice(index, offset).replace(reUnescapedString, escapeStringChar);

        // replace delimiters with snippets
        if (escapeValue) {
          source += "' +\n__e(" + escapeValue + ") +\n'";
        }
        if (evaluateValue) {
          isEvaluating = true;
          source += "';\n" + evaluateValue + ";\n__p += '";
        }
        if (interpolateValue) {
          source += "' +\n((__t = (" + interpolateValue + ")) == null ? '' : __t) +\n'";
        }
        index = offset + match.length;

        // the JS engine embedded in Adobe products requires returning the `match`
        // string in order to produce the correct `offset` value
        return match;
      });

      source += "';\n";

      // if `variable` is not specified, wrap a with-statement around the generated
      // code to add the data object to the top of the scope chain
      var variable = options.variable,
          hasVariable = variable;

      if (!hasVariable) {
        variable = 'obj';
        source = 'with (' + variable + ') {\n' + source + '\n}\n';
      }
      // cleanup code by stripping empty strings
      source = (isEvaluating ? source.replace(reEmptyStringLeading, '') : source)
        .replace(reEmptyStringMiddle, '$1')
        .replace(reEmptyStringTrailing, '$1;');

      // frame code as the function body
      source = 'function(' + variable + ') {\n' +
        (hasVariable ? '' : variable + ' || (' + variable + ' = {});\n') +
        "var __t, __p = '', __e = _.escape" +
        (isEvaluating
          ? ', __j = Array.prototype.join;\n' +
            "function print() { __p += __j.call(arguments, '') }\n"
          : ';\n'
        ) +
        source +
        'return __p\n}';

      // Use a sourceURL for easier debugging and wrap in a multi-line comment to
      // avoid issues with Narwhal, IE conditional compilation, and the JS engine
      // embedded in Adobe products.
      // http://www.html5rocks.com/en/tutorials/developertools/sourcemaps/#toc-sourceurl
      var sourceURL = '\n/*\n//@ sourceURL=' + (options.sourceURL || '/lodash/template/source[' + (templateCounter++) + ']') + '\n*/';

      try {
        var result = Function(importsKeys, 'return ' + source + sourceURL).apply(undefined, importsValues);
      } catch(e) {
        e.source = source;
        throw e;
      }
      if (data) {
        return result(data);
      }
      // provide the compiled function's source via its `toString` method, in
      // supported environments, or the `source` property as a convenience for
      // inlining compiled templates during the build process
      result.source = source;
      return result;
    }

    /**
     * Executes the `callback` function `n` times, returning an array of the results
     * of each `callback` execution. The `callback` is bound to `thisArg` and invoked
     * with one argument; (index).
     *
     * @static
     * @memberOf _
     * @category Utilities
     * @param {Number} n The number of times to execute the callback.
     * @param {Function} callback The function called per iteration.
     * @param {Mixed} [thisArg] The `this` binding of `callback`.
     * @returns {Array} Returns a new array of the results of each `callback` execution.
     * @example
     *
     * var diceRolls = _.times(3, _.partial(_.random, 1, 6));
     * // => [3, 6, 4]
     *
     * _.times(3, function(n) { mage.castSpell(n); });
     * // => calls `mage.castSpell(n)` three times, passing `n` of `0`, `1`, and `2` respectively
     *
     * _.times(3, function(n) { this.cast(n); }, mage);
     * // => also calls `mage.castSpell(n)` three times
     */
    function times(n, callback, thisArg) {
      n = (n = +n) > -1 ? n : 0;
      var index = -1,
          result = Array(n);

      callback = lodash.createCallback(callback, thisArg, 1);
      while (++index < n) {
        result[index] = callback(index);
      }
      return result;
    }

    /**
     * The inverse of `_.escape`, this method converts the HTML entities
     * `&amp;`, `&lt;`, `&gt;`, `&quot;`, and `&#39;` in `string` to their
     * corresponding characters.
     *
     * @static
     * @memberOf _
     * @category Utilities
     * @param {String} string The string to unescape.
     * @returns {String} Returns the unescaped string.
     * @example
     *
     * _.unescape('Moe, Larry &amp; Curly');
     * // => 'Moe, Larry & Curly'
     */
    function unescape(string) {
      return string == null ? '' : String(string).replace(reEscapedHtml, unescapeHtmlChar);
    }

    /**
     * Generates a unique ID. If `prefix` is passed, the ID will be appended to it.
     *
     * @static
     * @memberOf _
     * @category Utilities
     * @param {String} [prefix] The value to prefix the ID with.
     * @returns {String} Returns the unique ID.
     * @example
     *
     * _.uniqueId('contact_');
     * // => 'contact_104'
     *
     * _.uniqueId();
     * // => '105'
     */
    function uniqueId(prefix) {
      var id = ++idCounter;
      return String(prefix == null ? '' : prefix) + id;
    }

    /*--------------------------------------------------------------------------*/

    /**
     * Invokes `interceptor` with the `value` as the first argument, and then
     * returns `value`. The purpose of this method is to "tap into" a method chain,
     * in order to perform operations on intermediate results within the chain.
     *
     * @static
     * @memberOf _
     * @category Chaining
     * @param {Mixed} value The value to pass to `interceptor`.
     * @param {Function} interceptor The function to invoke.
     * @returns {Mixed} Returns `value`.
     * @example
     *
     * _([1, 2, 3, 4])
     *  .filter(function(num) { return num % 2 == 0; })
     *  .tap(alert)
     *  .map(function(num) { return num * num; })
     *  .value();
     * // => // [2, 4] (alerted)
     * // => [4, 16]
     */
    function tap(value, interceptor) {
      interceptor(value);
      return value;
    }

    /**
     * Produces the `toString` result of the wrapped value.
     *
     * @name toString
     * @memberOf _
     * @category Chaining
     * @returns {String} Returns the string result.
     * @example
     *
     * _([1, 2, 3]).toString();
     * // => '1,2,3'
     */
    function wrapperToString() {
      return String(this.__wrapped__);
    }

    /**
     * Extracts the wrapped value.
     *
     * @name valueOf
     * @memberOf _
     * @alias value
     * @category Chaining
     * @returns {Mixed} Returns the wrapped value.
     * @example
     *
     * _([1, 2, 3]).valueOf();
     * // => [1, 2, 3]
     */
    function wrapperValueOf() {
      return this.__wrapped__;
    }

    /*--------------------------------------------------------------------------*/

    // add functions that return wrapped values when chaining
    lodash.after = after;
    lodash.assign = assign;
    lodash.at = at;
    lodash.bind = bind;
    lodash.bindAll = bindAll;
    lodash.bindKey = bindKey;
    lodash.compact = compact;
    lodash.compose = compose;
    lodash.countBy = countBy;
    lodash.createCallback = createCallback;
    lodash.debounce = debounce;
    lodash.defaults = defaults;
    lodash.defer = defer;
    lodash.delay = delay;
    lodash.difference = difference;
    lodash.filter = filter;
    lodash.flatten = flatten;
    lodash.forEach = forEach;
    lodash.forIn = forIn;
    lodash.forOwn = forOwn;
    lodash.functions = functions;
    lodash.groupBy = groupBy;
    lodash.initial = initial;
    lodash.intersection = intersection;
    lodash.invert = invert;
    lodash.invoke = invoke;
    lodash.keys = keys;
    lodash.map = map;
    lodash.max = max;
    lodash.memoize = memoize;
    lodash.merge = merge;
    lodash.min = min;
    lodash.omit = omit;
    lodash.once = once;
    lodash.pairs = pairs;
    lodash.partial = partial;
    lodash.partialRight = partialRight;
    lodash.pick = pick;
    lodash.pluck = pluck;
    lodash.range = range;
    lodash.reject = reject;
    lodash.rest = rest;
    lodash.shuffle = shuffle;
    lodash.sortBy = sortBy;
    lodash.tap = tap;
    lodash.throttle = throttle;
    lodash.times = times;
    lodash.toArray = toArray;
    lodash.union = union;
    lodash.uniq = uniq;
    lodash.unzip = unzip;
    lodash.values = values;
    lodash.where = where;
    lodash.without = without;
    lodash.wrap = wrap;
    lodash.zip = zip;
    lodash.zipObject = zipObject;

    // add aliases
    lodash.chain = lodash;
    lodash.collect = map;
    lodash.drop = rest;
    lodash.each = forEach;
    lodash.extend = assign;
    lodash.methods = functions;
    lodash.object = zipObject;
    lodash.select = filter;
    lodash.tail = rest;
    lodash.unique = uniq;

    // add functions to `lodash.prototype`
    mixin(lodash);

    /*--------------------------------------------------------------------------*/

    // add functions that return unwrapped values when chaining
    lodash.clone = clone;
    lodash.cloneDeep = cloneDeep;
    lodash.contains = contains;
    lodash.escape = escape;
    lodash.every = every;
    lodash.find = find;
    lodash.findIndex = findIndex;
    lodash.findKey = findKey;
    lodash.has = has;
    lodash.identity = identity;
    lodash.indexOf = indexOf;
    lodash.isArguments = isArguments;
    lodash.isArray = isArray;
    lodash.isBoolean = isBoolean;
    lodash.isDate = isDate;
    lodash.isElement = isElement;
    lodash.isEmpty = isEmpty;
    lodash.isEqual = isEqual;
    lodash.isFinite = isFinite;
    lodash.isFunction = isFunction;
    lodash.isNaN = isNaN;
    lodash.isNull = isNull;
    lodash.isNumber = isNumber;
    lodash.isObject = isObject;
    lodash.isPlainObject = isPlainObject;
    lodash.isRegExp = isRegExp;
    lodash.isString = isString;
    lodash.isUndefined = isUndefined;
    lodash.lastIndexOf = lastIndexOf;
    lodash.mixin = mixin;
    lodash.noConflict = noConflict;
    lodash.parseInt = parseInt;
    lodash.random = random;
    lodash.reduce = reduce;
    lodash.reduceRight = reduceRight;
    lodash.result = result;
    lodash.runInContext = runInContext;
    lodash.size = size;
    lodash.some = some;
    lodash.sortedIndex = sortedIndex;
    lodash.template = template;
    lodash.unescape = unescape;
    lodash.uniqueId = uniqueId;

    // add aliases
    lodash.all = every;
    lodash.any = some;
    lodash.detect = find;
    lodash.foldl = reduce;
    lodash.foldr = reduceRight;
    lodash.include = contains;
    lodash.inject = reduce;

    forOwn(lodash, function(func, methodName) {
      if (!lodash.prototype[methodName]) {
        lodash.prototype[methodName] = function() {
          var args = [this.__wrapped__];
          push.apply(args, arguments);
          return func.apply(lodash, args);
        };
      }
    });

    /*--------------------------------------------------------------------------*/

    // add functions capable of returning wrapped and unwrapped values when chaining
    lodash.first = first;
    lodash.last = last;

    // add aliases
    lodash.take = first;
    lodash.head = first;

    forOwn(lodash, function(func, methodName) {
      if (!lodash.prototype[methodName]) {
        lodash.prototype[methodName]= function(callback, thisArg) {
          var result = func(this.__wrapped__, callback, thisArg);
          return callback == null || (thisArg && typeof callback != 'function')
            ? result
            : new lodashWrapper(result);
        };
      }
    });

    /*--------------------------------------------------------------------------*/

    /**
     * The semantic version number.
     *
     * @static
     * @memberOf _
     * @type String
     */
    lodash.VERSION = '1.2.1';

    // add "Chaining" functions to the wrapper
    lodash.prototype.toString = wrapperToString;
    lodash.prototype.value = wrapperValueOf;
    lodash.prototype.valueOf = wrapperValueOf;

    // add `Array` functions that return unwrapped values
    each(['join', 'pop', 'shift'], function(methodName) {
      var func = arrayProto[methodName];
      lodash.prototype[methodName] = function() {
        return func.apply(this.__wrapped__, arguments);
      };
    });

    // add `Array` functions that return the wrapped value
    each(['push', 'reverse', 'sort', 'unshift'], function(methodName) {
      var func = arrayProto[methodName];
      lodash.prototype[methodName] = function() {
        func.apply(this.__wrapped__, arguments);
        return this;
      };
    });

    // add `Array` functions that return new wrapped values
    each(['concat', 'slice', 'splice'], function(methodName) {
      var func = arrayProto[methodName];
      lodash.prototype[methodName] = function() {
        return new lodashWrapper(func.apply(this.__wrapped__, arguments));
      };
    });

    // avoid array-like object bugs with `Array#shift` and `Array#splice`
    // in Firefox < 10 and IE < 9
    if (!support.spliceObjects) {
      each(['pop', 'shift', 'splice'], function(methodName) {
        var func = arrayProto[methodName],
            isSplice = methodName == 'splice';

        lodash.prototype[methodName] = function() {
          var value = this.__wrapped__,
              result = func.apply(value, arguments);

          if (value.length === 0) {
            delete value[0];
          }
          return isSplice ? new lodashWrapper(result) : result;
        };
      });
    }

    // add pseudo private property to be used and removed during the build process
    lodash._each = each;
    lodash._iteratorTemplate = iteratorTemplate;
    lodash._shimKeys = shimKeys;

    return lodash;
  }

  /*--------------------------------------------------------------------------*/

  // expose Lo-Dash
  var _ = runInContext();

  // some AMD build optimizers, like r.js, check for specific condition patterns like the following:
  if (typeof define == 'function' && typeof define.amd == 'object' && define.amd) {
    // Expose Lo-Dash to the global object even when an AMD loader is present in
    // case Lo-Dash was injected by a third-party script and not intended to be
    // loaded as a module. The global assignment can be reverted in the Lo-Dash
    // module via its `noConflict()` method.
    window._ = _;

    // define as an anonymous module so, through path mapping, it can be
    // referenced as the "underscore" module
    define(function() {
      return _;
    });
  }
  // check for `exports` after `define` in case a build optimizer adds an `exports` object
  else if (freeExports && !freeExports.nodeType) {
    // in Node.js or RingoJS v0.8.0+
    if (freeModule) {
      (freeModule.exports = _)._ = _;
    }
    // in Narwhal or RingoJS v0.7.0-
    else {
      freeExports._ = _;
    }
  }
  else {
    // in a browser or Rhino
    window._ = _;
  }
}(this));