docs: def order_items(self, item_ids, assessment_part_id):
          """Reorders a set of items in an assessment part.
  
          arg:    item_ids (osid.id.Id[]): ``Ids`` for a set of ``Items``
          arg:    assessment_part_id (osid.id.Id): ``Id`` of the
                  ``AssessmentPartId``
          raise:  NotFound - ``assessment_part_id`` not found or, an
                  ``item_id`` not related to ``assessment_part_id``
          raise:  NullArgument - ``item_ids`` or ``agenda_id`` is ``null``
          raise:  OperationFailed - unable to complete request
          raise:  PermissionDenied - authorization failure
          *compliance: mandatory -- This method must be implemented.*
  
          """
          if (not isinstance(assessment_part_id, ABCId) and
                  assessment_part_id.get_identifier_namespace() != 'assessment_authoring.AssessmentPart'):
              raise errors.InvalidArgument('the argument is not a valid OSID Id')
          assessment_part_map, collection = self._get_assessment_part_collection(assessment_part_id)
          assessment_part_map['itemIds'] = order_ids(item_ids, assessment_part_map['itemIds'])
          collection.save(assessment_part_map)