title: Idiomatic way to unpack variable length list of maximum size n
body: <p>I'm reading a file and unpacking each line like this:</p>
  
  <pre><code>for line in filter(fh):
    a, b, c, d = line.split()
  </code></pre>
  
  <p>However, it's possible that line may have more or fewer columns than the variables I wish to unpack. In the case when there are fewer, I'd like to assign <code>None</code> to the dangling variables, and in the case where there are more, I'd like to ignore them. What's the idiomatic way to do this? I'm using python 2.7.</p>