@abc.abstractmethod<EOL><INDENT>def get_superseding_event_notification_session(self, superseding_event_receiver, proxy):<DEDENT>
return<EOL>
Gets the notification session for notifications pertaining to superseding event changes.

        :param superseding_event_receiver: the superseding event receiver
        :type superseding_event_receiver: ``osid.calendaring.SupersedingEventReceiver``
        :param proxy: a proxy
        :type proxy: ``osid.proxy.Proxy``
        :return: a ``SupersedingEventNotificationSession``
        :rtype: ``osid.calendaring.SupersedingEventNotificationSession``
        :raise: ``NullArgument`` -- ``superseding_event_receiver`` or ``proxy`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``Unimplemented`` -- ``supports_superseding_event_notification()`` is ``false``

        *compliance: optional -- This method must be implemented if
        ``supports_superseding_event_notification()`` is ``true``.*