title: Python 3 list(dictionary.keys()) raises error. What am I doing wrong?
body: <p>Dictionary:</p>
  
  <pre><code>error['extras'] = {'expiration_month': 'Invalid field [expiration_month] - Missing field "expiration_month"'}
  </code></pre>
  
  <p>Code:</p>
  
  <pre><code>list(error['extras'].keys())
  </code></pre>
  
  <p>Result:</p>
  
  <pre><code>*** Error in argument: "(error['extras'].keys())"
  </code></pre>
  
  <p>If its relevant, I'm running this code in a django process that's paused by pdb.set_trace().</p>