code: func Gone(w http.ResponseWriter, r *http.Request) {
  	handlerMu.RLock()
  	f, ok := handlerMap[http.StatusGone]
  	handlerMu.RUnlock()
  	if ok {
  		f.ServeHTTP(w, r)
  	} else {
  		defaultGone(w, r)
  	}
  }
docs: // Gone responds to the request with a 410 Gone error message