code: def write_to_datastore(self):
      
      client = self._datastore_client
      with client.no_transact_batch() as client_batch:
        for batch_id, batch_data in iteritems(self._data):
          batch_key = client.key(self._entity_kind_batches, batch_id)
          batch_entity = client.entity(batch_key)
          for k, v in iteritems(batch_data):
            if k != 'images':
              batch_entity[k] = v
          client_batch.put(batch_entity)
          self._write_single_batch_images_internal(batch_id, client_batch)
docs: Writes all image batches to the datastore.