code: func (w *appResponseWriter) Write(data []byte) (n int, err error) {
  	if w.statusCode == 0 {
  		w.statusCode = http.StatusOK
  	}
  	size, err := w.ResponseWriter.Write(data)
  	w.size += size
  	return size, err
  }
docs: // Don't need this yet because we get it for free: