def _add_keys_to_request(request_field_pb, key_pbs):
    """Add protobuf keys to a request object.

    :type request_field_pb: `RepeatedCompositeFieldContainer`
    :param request_field_pb: A repeated proto field that contains keys.

    :type key_pbs: list of :class:`gcloud.datastore._generated.entity_pb2.Key`
    :param key_pbs: The keys to add to a request.
    """
    for key_pb in key_pbs:
        request_field_pb.add().CopyFrom(key_pb)
