code: def get_assessment_part(self):
          
          if not self.has_parent_part():
              raise errors.IllegalState('no parent part')
          lookup_session = self._get_assessment_part_lookup_session()
          return lookup_session.get_assessment_part(self.get_assessment_part_id())
docs: Gets the parent assessment.
  
          return: (osid.assessment.authoring.AssessmentPart) - the parent
                  assessment part
          raise:  IllegalState - ``has_parent_part()`` is ``false``
          raise:  OperationFailed - unable to complete request
          *compliance: mandatory -- This method must be implemented.*