Return true if the given string is a palindrome. Otherwise, return false.

A palindrome is a word or sentence that's spelled the same way both forward and backward, ignoring punctuation, case, and spacing.

You'll need to remove all non-alphanumeric characters (punctuation, spaces and symbols) and turn everything into the same case (lower or upper case) in order to check for palindromes.

For starters you'll have to clear the string from all the non-alphanumerical characters, so:

* Create a function to identify all non-alphanumerical characters

* Create a function that parses a list of characters and using the first function deletes all non-alphanumerical characters

* In our main function, we have to call the second function we wrote, and pass as arguments our string (as lowercase), as a list of characters.

* list.splice(index, 1) -> removes a list's item by index

* str.toLowerCase() -> converts a string to lowercase letters

* str.split("") -> splits a string into an array of substrings, and returns the new array