python chaining
<p><strong>Updated</strong></p>

<p>Let's say I have:</p>

<pre><code>dic={"z":"zv", "a":"av"}
## why doesn't the following return a sorted list of keys?
keys=dic.keys().sort()
</code></pre>

<p>I know I could do the following and have the proper result:</p>

<pre><code>dic={"z":"zv", "a":"av"}
keys=dic.keys()
skeys=keys.sort()  ### skeys will be None
</code></pre>

<p>Why doesn't the first example work?</p>
