Why doesn't [].extend(list1) create an identical list to list1?
<blockquote>
  <p><strong>Possible Duplicate:</strong><br>
  <a href="http://stackoverflow.com/questions/9724356/python-list-extension-and-variable-assignment">Python list extension and variable assignment</a>  </p>
</blockquote>



<p>The analogue for strings holds true:</p>

<pre><code>string1 = 'abc'
''.join(string1) == string1 # True
</code></pre>

<p>So why doesn't this hold true:</p>

<pre><code>list1 = ['a', 'b', 'c']
[].extend(list1) == list1 # AttributeError: 'NoneType' object has no attribute 'extend'
</code></pre>

<p><code>type([])</code> returns list. Why would it get perceived as a NoneType instead of a list which would have the extend method?</p>

<p>This is an academic question. I wouldn't do this is regular code, I just want to understand.</p>
