title: How to override equals() in google app engine data model type?
body: <p>I'm using the Python libraries for Google App Engine.  How can I override the <code>equals()</code> method on a class so that it judges equality on the <code>user_id</code> field of the following class:</p>
  
  <pre><code>class UserAccount(db.Model):
      # compare all equality tests on user_id
      user = db.UserProperty(required=True)
      user_id = db.StringProperty(required=True)
      first_name = db.StringProperty()
      last_name = db.StringProperty()
      notifications = db.ListProperty(db.Key)
  </code></pre>
  
  <p>Right now, I'm doing equalty by getting a <code>UserAccount</code> object and doing <code>user1.user_id == user2.user_id</code>.  Is there a way I can override it so that 'user1 == user2' will look at only the 'user_id' fields?</p>
  
  <p>Thanks in advance </p>