def get_child_objective_ids(self, objective_id=None):
if objective_id is None:<EOL><INDENT>raise NullArgument()<EOL><DEDENT>url_path = construct_url('<STR_LIT>',<EOL>bank_id=self._catalog_idstr,<EOL>obj_id=objective_id)<EOL>id_list = list()<EOL>for identifier in self._get_request(url_path)['<STR_LIT>']:<EOL><INDENT>id_list.append(Id(idstr=identifier))<EOL><DEDENT>return id_objects.IdList(id_list)<EOL>
Gets the child Ids of the given objective.

        arg:    objective_id (osid.id.Id): the Id to query
        return: (osid.id.IdList) - the children of the objective
        raise:  NotFound - objective_id is not found
        raise:  NullArgument - objective_id is null
        raise:  OperationFailed - unable to complete request
        raise:  PermissionDenied - authorization failure
        compliance: mandatory - This method must be implemented.