code: func (r ProtoBuf) Render(w http.ResponseWriter) error {
  	r.WriteContentType(w)
  
  	bytes, err := proto.Marshal(r.Data.(proto.Message))
  	if err != nil {
  		return err
  	}
  
  	_, err = w.Write(bytes)
  	return err
  }
docs: // Render (ProtoBuf) marshals the given interface object and writes data with custom ContentType.