title: Sorting a list of unix time stamp values
body: <p>Given a list of UNIX time stamp values:</p>
  
  <pre><code>l = ['1260633600', '1256993100', '1273255200', '1253450700']
  </code></pre>
  
  <p>I need the list to be sorted. </p>
  
  <pre><code>from datetime import datetime
  def humanize_unixtime(unix_time):
      time = datetime.fromtimestamp(int(unix_time)).strftime('%d-%m-%Y %H.%M')
      return time 
  
  lsorted = sorted(l, key=lambda x: humanize_unixtime(x), reverse=True)
  print [humanize_unixtime(i) for i in lsorted]
  </code></pre>
  
  <p>When I run this, I got <code>['31-10-2009 13.45', '20-09-2009 14.45', '12-12-2009 17.00', '07-05-2010 20.00']</code>, which is not at all sorted. Can you see what's wrong?</p>