code: func WithSignals(sig ...os.Signal) Process {
  	p := WithParent(Background())
  	c := make(chan os.Signal)
  	signal.Notify(c, sig...)
  	go func() {
  		<-c
  		signal.Stop(c)
  		p.Close()
  	}()
  	return p
  }
docs: // WithSignals returns a Process that will Close() when any given signal fires.
  // This is useful to bind Process trees to syscall.SIGTERM, SIGKILL, etc.