What is the effect of "list=list" in Python modules?
<p>I've seen following code in the python standard library <code>/usr/lib/python2.7/multiprocessing/dummy/__init__.py</code>:</p>

<pre><code>list = list
dict = dict
</code></pre>

<p>What does this idiom mean? My best guess is: "let's check if <code>dict</code> and <code>list</code> exist".
Is it just legacy code from the ancient times without <code>list</code> and <code>dict</code> in the <code>__builtins__</code>?</p>

<p>And I have another mad guess: <em>optimization</em> of lookup speed moving <code>list</code> from global scope to module scope. Is it sane assumption regarding the idiom? I see, that the assumption is wrong if I apply it to multiprocessing.</p>
