@abc.abstractmethod<EOL><INDENT>def get_repository_notification_session(self, repository_receiver, proxy):<DEDENT>
return<EOL>
Gets the notification session for subscribing to changes to a repository.

        :param repository_receiver: the notification callback
        :type repository_receiver: ``osid.repository.RepositoryReceiver``
        :param proxy: a proxy
        :type proxy: ``osid.proxy.Proxy``
        :return: a ``RepositoryNotificationSession``
        :rtype: ``osid.repository.RepositoryNotificationSession``
        :raise: ``NullArgument`` -- ``repository_receiver`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``Unimplemented`` -- ``supports_repository_notification()`` is ``false``

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