title: Google App Engine - Error: Model constructor takes no positional arguments
body: <p>I have the following code to try to create a message with a default value:</p>
  
  <pre><code>MESSAGE_STORE = "messages"
  def get_message_key(key_name=MESSAGE_STORE):
      return ndb.Key("Message", key_name)
  
  def save_message(msg):
    message = Message(parent=get_message_key(MESSAGE_STORE), message=msg)
    message.put()
  
  class Message(ndb.Model):
      message = ndb.StringProperty(indexed=False)
      def __init__(self, *args, **kwargs):
        super(Message, self).__init__(self)
        self.message = kwargs.get('message', 'No Message')
  </code></pre>
  
  <p>I get the error ever time, though.  How can I call this properly, it works fine if I just have no constructor and call it with: </p>
  
  <pre><code>message = Message(parent=get_message_key(MESSAGE_STORE))
  message.message = "Test Message"
  </code></pre>
  
  <p>What is with the error?</p>