title: Sessions enabled - do we have to clean them up ourselves?
body: <p>When we turn sessions on in google app engine like:</p>
  
  <pre><code>// appengine-web.xml
  &lt;sessions-enabled&gt;true&lt;/sessions-enabled&gt;
  </code></pre>
  
  <p>does app engine automatically clean up expired sessions, or do we have to do it ourselves? After turning them on, I see in the datastore that some entries are being generated like _ah_session, I'm wondering if those are them? </p>
  
  <p>Thanks</p>