code: def _get_first_part_id(self, assessment_id):
          
          if assessment_id not in self._first_part_index:
              self._first_part_index[assessment_id] = get_first_part_id_for_assessment(
                  assessment_id,
                  runtime=self._runtime,
                  proxy=self._proxy,
                  create=True,
                  bank_id=self._catalog_id)
          return self._first_part_index[assessment_id]
docs: This session implemenation assumes all items are assigned to the first assessment part