code: func DeletionHandlingMetaNamespaceKeyFunc(obj interface{}) (string, error) {
  	if d, ok := obj.(DeletedFinalStateUnknown); ok {
  		return d.Key, nil
  	}
  	return MetaNamespaceKeyFunc(obj)
  }
docs: // DeletionHandlingMetaNamespaceKeyFunc checks for
  // DeletedFinalStateUnknown objects before calling
  // MetaNamespaceKeyFunc.