Why am I unable to assign to a particular element in a list of lists
<p>I don't understand why I am assigning to the first element in every list below:</p>

<pre><code>➜  ~  python
Python 2.7.3 (default, Sep 26 2012, 21:53:58) 
[GCC 4.7.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
&gt;&gt;&gt; board = [[None]*5]*5
&gt;&gt;&gt; print board
[[None, None, None, None, None], [None, None, None, None, None], [None, None, None, None, None], [None, None, None, None, None], [None, None, None, None, None]]
&gt;&gt;&gt; board[0][0] = 1
&gt;&gt;&gt; print board
[[1, None, None, None, None], [1, None, None, None, None], [1, None, None, None, None], [1, None, None, None, None], [1, None, None, None, None]]
</code></pre>

<p>I would expect the final output to be this:</p>

<pre><code>[[1, None, None, None, None], [None, None, None, None, None], [None, None, None, None, None], [None, None, None, None, None], [None, None, None, None, None]]
</code></pre>
