def get_group_notification_session(self, group_rceeiver=None):
raise Unimplemented()<EOL>
Gets the notification session for notifications pertaining to resource changes.

        arg:    group_rceeiver (osid.resource.GroupReceiver): the
                notification callback
        return: (osid.resource.GroupNotificationSession) - ``a
                GroupNotificationSession``
        raise:  NullArgument - ``group_receiver`` is ``null``
        raise:  OperationFailed - unable to complete request
        raise:  Unimplemented - ``supports_group_notification()`` is
                ``false``
        *compliance: optional -- This method must be implemented if
        ``supports_group_notification()`` is ``true``.*