title: 'NoneType' object has no attribute 'keys'
body: <p>When running my code i am using</p>
  
  <pre><code>for line in open(INPUT_LOGS).readlines()[:MAX_ROWS]: 
      a = parse_line(line)
  
  if headers is None:
      header = a.keys()
  </code></pre>
  
  <p>and I am getting the above error.</p>