title: proper use of list comprehensions - python
body: <p>Normally, list comprehensions are used to derive a new list from an existing list. Eg:</p>
  
  <pre><code>&gt;&gt;&gt; a = [1, 2, 3, 4, 5]
  &gt;&gt;&gt; [i for i in a if i &gt; 2]
  [3, 4, 5]
  </code></pre>
  
  <p>Should we use them to perform other procedures? Eg:</p>
  
  <pre><code>&gt;&gt;&gt; a = [1, 2, 3, 4, 5]
  &gt;&gt;&gt; b = []
  &gt;&gt;&gt; [b.append(i) for i in a]
  [None, None, None, None, None]
  &gt;&gt;&gt; print b
  [1, 2, 3, 4, 5]
  </code></pre>
  
  <p>or should I avoid the above and use the following instead?:</p>
  
  <pre><code>for i in a:
      b.append(i)
  </code></pre>