code: def read_batch_from_datastore(self, class_batch_id):
      
      client = self._datastore_client
      key = client.key(KIND_CLASSIFICATION_BATCH, class_batch_id)
      result = client.get(key)
      if result is not None:
        return dict(result)
      else:
        raise KeyError(
            'Key {0} not found in the datastore'.format(key.flat_path))
docs: Reads and returns single batch from the datastore.