code: func Unauthorized(w http.ResponseWriter, r *http.Request, domain string) {
  	handlerMu.RLock()
  	f, ok := handlerMap[http.StatusUnauthorized]
  	handlerMu.RUnlock()
  	if ok {
  		r = ctxSetDomain(r, domain)
  		f.ServeHTTP(w, r)
  	} else {
  		defaultUnauthorized(w, r, domain)
  	}
  }
docs: // Unauthorized sets the Domain in the request context