title: Using ndb.KeyProperty how to reference the same model?
body: <p>I have a simple scenario where there is a User class which has the name, email and followers property. </p>
  
  <pre><code>class User(ndb.Model):
      name = ndb.StringProperty(required = True)
      search_name = ndb.StringProperty(required = True)
      pw_hash = ndb.StringProperty(required = True)
      email = ndb.StringProperty()
  
      follows = ndb.KeyProperty(Follow, repeated=True)
      followers = ndb.KeyProperty(User, repeated=True)
  </code></pre>
  
  <p>While executing this I am getting the error.</p>
  
  <pre><code>File "C:\ujjal\my project\cravel\code2\Users.py", line 46, in User
    followers = ndb.KeyProperty(User, repeated=True)
  NameError: name 'User' is not defined
  INFO     2012-09-11 11:45:23,953 dev_appserver.py:2967] "GET / HTTP/1.1" 500 -
  </code></pre>
  
  <p>Any suggestion as to how model the "followers" attribute would be highly appreciated.
  Thanks in Advance</p>