def get_relationship_notification_session(self, relationship_receiver=None):
pass<EOL>
Gets the ``OsidSession`` associated with the relationship notification service.

        arg:    relationship_receiver
                (osid.relationship.RelationshipReceiver): the receiver
        return: (osid.relationship.RelationshipNotificationSession) - a
                ``RelationshipNotificationSession``
        raise:  NullArgument - ``relationship_receiver`` is ``null``
        raise:  OperationFailed - unable to complete request
        raise:  Unimplemented - ``supports_relationship_notification()``
                is ``false``
        *compliance: optional -- This method must be implemented if ``supports_relationship_notification()`` is ``true``.*