code: func normalizeOne(ctx context.Context, in []byte, p *configPair) (out []byte, err error) {
  	msg := reflect.New(p.typ.Elem()).Interface().(proto.Message)
  	if err = luciproto.UnmarshalTextML(string(in), msg); err != nil {
  		return
  	}
  	if err = p.protoNormalizer(ctx, msg); err != nil {
  		return
  	}
  	return []byte(proto.MarshalTextString(msg)), nil
  }
docs: // normalizeOne deserializes the proto, passes it through normalizer, serializes
  // it back.