title: Week number for US format on Python
body: <p>I'm trying to get week number with this simple script on python. </p>
  
  <pre><code>import datetime
  
  t = datetime.date(2013,8,18)
  print t.isocalendar()[1]
  </code></pre>
  
  <p>It returns 33 for ISO format, but for the US calendar it should be 34.
  How can I get this week number for US format?</p>