This session implemenation assumes all items are assigned to the first assessment part

def _get_first_part_id(self, assessment_id):
        """This session implemenation assumes all items are assigned to the first assessment part"""
        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]