code: func (s *Server) RemoveFailedNode(node string) error {
  	if err := s.serfLAN.RemoveFailedNode(node); err != nil {
  		return err
  	}
  	if s.serfWAN != nil {
  		if err := s.serfWAN.RemoveFailedNode(node); err != nil {
  			return err
  		}
  	}
  	return nil
  }
docs: // RemoveFailedNode is used to remove a failed node from the cluster