@abc.abstractmethod<EOL><INDENT>def get_group_notification_session(self, group_rceeiver, proxy):<DEDENT>
return<EOL>
Gets the notification session for notifications pertaining to resource changes.

        :param group_rceeiver: the notification callback
        :type group_rceeiver: ``osid.resource.GroupReceiver``
        :param proxy: a proxy
        :type proxy: ``osid.proxy.Proxy``
        :return: ``a GroupNotificationSession``
        :rtype: ``osid.resource.GroupNotificationSession``
        :raise: ``NullArgument`` -- ``group_receiver`` or ``proxy`` 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``.*