func (s *Server) ListenAndServeUNIX(addr string, mode os.FileMode) error {
	if err := os.Remove(addr); err != nil && !os.IsNotExist(err) {
		return fmt.Errorf("unexpected error when trying to remove unix socket file %q: %s", addr, err)
	}
	ln, err := net.Listen("unix", addr)
	if err != nil {
		return err
	}
	if err = os.Chmod(addr, mode); err != nil {
		return fmt.Errorf("cannot chmod %#o for %q: %s", mode, addr, err)
	}
	return s.Serve(ln)
}
func (s *Server) ListenAndServeUNIX(addr string, mode os.FileMode) error {
	if err := os.Remove(addr); err != nil && !os.IsNotExist(err) {
		return fmt.Errorf("unexpected error when trying to remove unix socket file %q: %s", addr, err)
	}
	ln, err := net.Listen("unix", addr)
	if err != nil {
		return err
	}
	if err = os.Chmod(addr, mode); err != nil {
		return fmt.Errorf("cannot chmod %#o for %q: %s", mode, addr, err)
	}
	return s.Serve(ln)
}
// ListenAndServeUNIX serves HTTP requests from the given UNIX addr.
//
// The function deletes existing file at addr before starting serving.
//
// The server sets the given file mode for the UNIX addr.