title: Datetime differences on python
body: <p>I have  DateTime, from string I convert them on IS0 format example. <code>ISODate("2016-06-24T09:07:31.097Z")</code> </p>
  
  <p>I want to find the differences between them using python, so I did this:</p>
  
  <pre><code>string_older = "2016-05-18T20:53:43.776456"
  string_young = "2016-05-16T20:53:43.776456"
  datetime_older = datetime.datetime.strptime(string_older, "%Y-%m-%dT%H:%M:%S.%f") //date on ISO format
  datetime_young = datetime.datetime.strptime(string_young, "%Y-%m-%dT%H:%M:%S.%f") //date on ISO format
  a = time.mktime(datetime_older)
  b = time.mktime(datetime_young)
  diff = a - b
  seconds = int(diff) % 60
  </code></pre>
  
  <p>But this gives this error <code>TypeError: argument must be 9-item sequence, not datetime.datetime</code> 
  at this line <code>time.mktime(datetime_older)</code>.
  I don't know how to fix it? Please help.</p>