title: The if statement in a list comprehension
body: <pre><code>&gt;&gt;&gt; row = [1,2,3,4,"--"]
  &gt;&gt;&gt; row = [cell.replace("--","hello") for cell in row if cell == "--"]
  &gt;&gt;&gt; row
  ['hello']
  </code></pre>
  
  <p>How can I get <code>[1,2,3,4,"hello"]</code> with a list comprehension?</p>