@abc.abstractmethod<EOL><INDENT>def get_agent_notification_session(self, agent_receiver):<DEDENT>
return<EOL>
Gets the notification session for notifications pertaining to service changes.

        :param agent_receiver: the agent receiver
        :type agent_receiver: ``osid.authentication.AgentReceiver``
        :return: an ``AgentNotificationSession``
        :rtype: ``osid.authentication.AgentNotificationSession``
        :raise: ``NullArgument`` -- ``agent_receiver`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``Unimplemented`` -- ``supports_agent_notification()`` is ``false``

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