@classmethod
def get_by_auth_id(cls, auth_id):
    """Returns a user object based on a auth_id.

        :param auth_id:
            String representing a unique id for the user. Examples:

            - own:username
            - google:username
        :returns:
            A user object.
        """
    return cls.query(cls.auth_ids == auth_id).get()
