code: func (f DebugFlags) Index(w http.ResponseWriter, r *http.Request) {
  	lock.RLock()
  	defer lock.RUnlock()
  	if err := indexTmpl.Execute(w, registeredFlags); err != nil {
  		klog.Error(err)
  	}
  }
docs: // Index responds with the `/debug/flags` request.
  // For example, "/debug/flags/v" serves the "--v" flag.
  // Index responds to a request for "/debug/flags/" with an HTML page
  // listing the available flags.