Save entities in the Cloud Datastore.

        :type entities: list of :class:`google.cloud.datastore.entity.Entity`
        :param entities: The entities to be saved to the datastore.

        :raises: :class:`ValueError` if ``entities`` is a single entity.

def put_multi(self, entities):
        """Save entities in the Cloud Datastore.

        :type entities: list of :class:`google.cloud.datastore.entity.Entity`
        :param entities: The entities to be saved to the datastore.

        :raises: :class:`ValueError` if ``entities`` is a single entity.
        """
        if isinstance(entities, Entity):
            raise ValueError("Pass a sequence of entities")

        if not entities:
            return

        current = self.current_batch
        in_batch = current is not None

        if not in_batch:
            current = self.batch()
            current.begin()

        for entity in entities:
            current.put(entity)

        if not in_batch:
            current.commit()