code: func toTextPb(_ *starlark.Thread, _ *starlark.Builtin, args starlark.Tuple, kwargs []starlark.Tuple) (starlark.Value, error) {
  	var msg *Message
  	if err := starlark.UnpackArgs("to_textpb", args, kwargs, "msg", &msg); err != nil {
  		return nil, err
  	}
  	pb, err := msg.ToProto()
  	if err != nil {
  		return nil, err
  	}
  	return starlark.String(proto.MarshalTextString(pb)), nil
  }
docs: // toTextPb takes a single protobuf message and serializes it using text
  // protobuf serialization.