title: python list appending is not working
body: <p>I have something similar to:</p>
  
  <pre><code>&gt;&gt;&gt; S=list()
  &gt;&gt;&gt; T=[1,2,3]
  &gt;&gt;&gt; for t in T:
  ...     print(S.append(t))
  </code></pre>
  
  <p>The output I am getting is:</p>
  
  <pre><code>...
  None
  None
  None
  </code></pre>
  
  <p>I expect S contains t. Why this is not working with me ?</p>