title: Automatic deletion or expiration of GAE datastore entities
body: <p>I'm building my first app with GAE to allow users to run elections, and I create an Election entity for each election.  </p>
  
  <p>To avoid storing too much data, I'd like to automatically delete an Election entity after a certain period of time -- say three months after the end of the election.  Is it possible to do this automatically in GAE?  Or do I need to do this manually?</p>
  
  <p>If it matters, I'm using the Python interface.</p>