from collections import deque

<deque> = deque(<collection>, maxlen=None)

<deque>.appendleft(<el>) # Opposite element is dropped if full.

<el> = <deque>.popleft() # Raises IndexError if empty.

<deque>.extendleft(<collection>) # Collection gets reversed.

<div><h2 id="deque"><a href="#deque" name="deque">#</a>Deque</h2><p><strong>A thread-safe list with efficient appends and pops from either side. Pronounced "deck".</strong></p><pre><code class="python language-python hljs"><span class="hljs-keyword">from</span> collections <span class="hljs-keyword">import</span> deque

&lt;deque&gt; = deque(&lt;collection&gt;, maxlen=<span class="hljs-keyword">None</span>)

<div><h2 id="threading"><a href="#threading" name="threading">#</a>Threading</h2><ul>

<li><strong>CPython interpreter can only run a single thread at a time.</strong></li>

<li><strong>That is why using multiple threads won't result in a faster execution, unless there is an I/O operation in the thread.</strong></li>

&lt;Image&gt;.putdata(&lt;list/ImagingCore&gt;) <span class="hljs-comment"># Writes a sequence of pixels.</span>

&lt;Image&gt;.paste(&lt;Image&gt;, (x, y)) <span class="hljs-comment"># Writes an image to image.</span>

<div><h3 id="modes-1">Modes</h3><ul>

<li><strong><code class="python hljs"><span class="hljs-string">'1'</span></code> - 1-bit pixels, black and white, stored with one pixel per byte.</strong></li>