title: What is the inverse of date.toordinal() in python?
body: <p>In python, a <code>date</code>object can be converted in the proleptic Gregorian ordinal this way:</p>
  
  <pre><code>d=datetime.date(year=2010, month=3, day=1)
  d.toordinal()
  </code></pre>
  
  <p>but what is the reverse operation?</p>