def get_catalog_assignment_session(self):
raise Unimplemented()<EOL>
Gets the cataloging session for adding and removing mappings to catalogs.

        return: (osid.cataloging.CatalogAssignmentSession) - a
                ``CatalogAssignmentSession``
        raise:  OperationFailed - unable to complete request
        raise:  Unimplemented - ``supports_catalog_assignment()`` is
                ``false``
        *compliance: optional -- This method must be implemented if
        ``supports_catalog_assignment()`` is ``true``.*