def get_catalog_notification_session(self, catalog_receiver=None):
raise Unimplemented()<EOL>
Gets the notification session for subscribing to changes to catalogs.

        arg:    catalog_receiver (osid.cataloging.CatalogReceiver): the
                notification callback
        return: (osid.cataloging.CatalogNotificationSession) - a
                ``CatalogNotificationSession``
        raise:  NullArgument - ``catalog_receiver`` is ``null``
        raise:  OperationFailed - unable to complete request
        raise:  Unimplemented - ``supports_catalog_notification()`` is
                ``false``
        *compliance: optional -- This method must be implemented if
        ``supports_catalog_notification()`` is ``true``.*