code: func SystemdListeners() ([]net.Listener, error) {
  	pid, err := strconv.Atoi(os.Getenv("LISTEN_PID"))
  	if err != nil {
  		return nil, err
  	}
  	if pid != os.Getpid() {
  		return nil, nil
  	}
  	return restoreListeners("LISTEN_FDS")
  }
docs: // SystemdListeners returns listeners from systemd socket activation.