title: Checking if Entity exists in google app engine datastore.
body: <p>What is the best/fastest way to check if an Entity exists in a google-app-engine datastore?  For now I'm trying to get the entity by key and checking if the get() returns an error.</p>
  
  <p>I don't know the process of getting an Entity on the datastore. Is there a faster way for doing only this check?</p>