code: def get_child_gradebook_ids(self, gradebook_id):
          
          # Implemented from template for
          # osid.resource.BinHierarchySession.get_child_bin_ids
          if self._catalog_session is not None:
              return self._catalog_session.get_child_catalog_ids(catalog_id=gradebook_id)
          return self._hierarchy_session.get_children(id_=gradebook_id)
docs: Gets the child ``Ids`` of the given gradebook.
  
          arg:    gradebook_id (osid.id.Id): the ``Id`` to query
          return: (osid.id.IdList) - the children of the gradebook
          raise:  NotFound - ``gradebook_id`` is not found
          raise:  NullArgument - ``gradebook_id`` is ``null``
          raise:  OperationFailed - unable to complete request
          raise:  PermissionDenied - authorization failure
          *compliance: mandatory -- This method must be implemented.*