Gets the root gradebook ``Ids`` in this hierarchy.

        return: (osid.id.IdList) - the root gradebook ``Ids``
        raise:  OperationFailed - unable to complete request
        raise:  PermissionDenied - authorization failure
        *compliance: mandatory -- This method must be implemented.*

def get_root_gradebook_ids(self):
        """Gets the root gradebook ``Ids`` in this hierarchy.

        return: (osid.id.IdList) - the root gradebook ``Ids``
        raise:  OperationFailed - unable to complete request
        raise:  PermissionDenied - authorization failure
        *compliance: mandatory -- This method must be implemented.*

        """
        # Implemented from template for
        # osid.resource.BinHierarchySession.get_root_bin_ids
        if self._catalog_session is not None:
            return self._catalog_session.get_root_catalog_ids()
        return self._hierarchy_session.get_roots()