code: def _write_to_datastore(self):
      
      # Populate datastore
      roots_and_submissions = zip([ATTACKS_ENTITY_KEY,
                                   TARGET_ATTACKS_ENTITY_KEY,
                                   DEFENSES_ENTITY_KEY],
                                  [self._attacks,
                                   self._targeted_attacks,
                                   self._defenses])
      client = self._datastore_client
      with client.no_transact_batch() as batch:
        for root_key, submissions in roots_and_submissions:
          batch.put(client.entity(client.key(*root_key)))
          for k, v in iteritems(submissions):
            entity = client.entity(client.key(
                *(root_key + [KIND_SUBMISSION, k])))
            entity['submission_path'] = v.path
            entity.update(participant_from_submission_path(v.path))
            batch.put(entity)
docs: Writes all submissions to datastore.