code: func (f *featureGate) AddFlag(fs *pflag.FlagSet) {
  	f.lock.Lock()
  	// TODO(mtaufen): Shouldn't we just close it on the first Set/SetFromMap instead?
  	// Not all components expose a feature gates flag using this AddFlag method, and
  	// in the future, all components will completely stop exposing a feature gates flag,
  	// in favor of componentconfig.
  	f.closed = true
  	f.lock.Unlock()
  
  	known := f.KnownFeatures()
  	fs.Var(f, flagName, ""+
  		"A set of key=value pairs that describe feature gates for alpha/experimental features. "+
  		"Options are:\n"+strings.Join(known, "\n"))
  }
docs: // AddFlag adds a flag for setting global feature gates to the specified FlagSet.