func AddFeatureGatesStringFlag(fs *pflag.FlagSet, featureGatesString *string) {
	if knownFeatures := features.KnownFeatures(&features.InitFeatureGates); len(knownFeatures) > 0 {
		fs.StringVar(featureGatesString, FeatureGatesString, *featureGatesString, "A set of key=value pairs that describe feature gates for various features. "+
			"Options are:\n"+strings.Join(knownFeatures, "\n"))
	} else {

	}

	r := KnownFeatures(&someFeatures)

	if len(r) != 3 {
		t.Errorf("KnownFeatures returned %d values, expected 3", len(r))
	}

	// check the first value is feature1 (the list should be sorted); prerelease and default should be present
	f1 := "feature1=true|false (BETA - default=false)"
	if r[0] != f1 {
		t.Errorf("KnownFeatures returned %s values, expected %s", r[0], f1)
	}

		t.Fatal(err)
	}
	if err := knownFeatureGates.Add(defaultKubernetesFeatureGates); err != nil {
		t.Fatal(err)
	}
	knownFeatures := knownFeatureGates.GetAll()

	for registeredFeature := range registeredFeatures {
		if _, ok := knownFeatures[registeredFeature]; !ok {
			t.Errorf("The feature gate %q is not from known feature gates", registeredFeature)
		}
	}

	featureGateRegex := regexp.MustCompile("^([a-zA-Z0-9]+)")

	alphaFeatures := sets.NewString()
	for _, featureText := range utilfeature.DefaultFeatureGate.KnownFeatures() {
		// we have to parse this from KnownFeatures, because usage of mutable FeatureGate is not allowed in unit tests
		feature := featureGateRegex.FindString(featureText)

	for k := range featureList {
		if featureName == k {
			return true
		}
	}
	return false
}

// KnownFeatures returns a slice of strings describing the FeatureList features.
func KnownFeatures(f *FeatureList) []string {
	var known []string
	for k, v := range *f {
		if v.HiddenInHelpText {
			continue
		}

		pre := ""

	fs.Var(cliflag.NewMapStringBool(&c.FeatureGates), "feature-gates", "A set of key=value pairs that describe feature gates for alpha/experimental features. "+
		"Options are:\n"+strings.Join(utilfeature.DefaultFeatureGate.KnownFeatures(), "\n"))
	fs.StringVar(&c.KubeletCgroups, "kubelet-cgroups", c.KubeletCgroups, "Optional absolute name of cgroups to create and run the Kubelet in.")

	fs.Var(cliflag.NewMapStringBool(&o.config.FeatureGates), "feature-gates", "A set of key=value pairs that describe feature gates for alpha/experimental features. "+
		"Options are:\n"+strings.Join(utilfeature.DefaultFeatureGate.KnownFeatures(), "\n")+"\n"+
		"This parameter is ignored if a config file is specified by --config.")