docs: def get_child_assessment_parts(self):
          """Gets any child assessment parts.
  
          return: (osid.assessment.authoring.AssessmentPartList) - the
                  child assessment parts
          raise:  OperationFailed - unable to complete request
          *compliance: mandatory -- This method must be implemented.*
  
          """
          if not self.has_children():
              raise errors.IllegalState('no children assessment parts')
          # only returned unsequestered children?
          lookup_session = self._get_assessment_part_lookup_session()
          lookup_session.use_sequestered_assessment_part_view()
          return lookup_session.get_assessment_parts_by_ids(self.get_child_ids())