code: func IsCritical(ns string, annotations map[string]string) bool {
  	// Critical pods are restricted to "kube-system" namespace as of now.
  	if ns != kubeapi.NamespaceSystem {
  		return false
  	}
  	val, ok := annotations[CriticalPodAnnotationKey]
  	if ok && val == "" {
  		return true
  	}
  	return false
  }
docs: // IsCritical returns true if parameters bear the critical pod annotation
  // key. The DaemonSetController use this key directly to make scheduling decisions.
  // TODO: @ravig - Deprecated. Remove this when we move to resolving critical pods based on priorityClassName.