ps := pubsub.New()
ps.Sub(func(i int) {
    fmt.Println("int subscriber: ", i)
})

ps.Pub(1)

// global
var ps = pubsub.New()
// subscribe with a network connection
func Subscribe(conn net.Conn) {
	f := func(i int) { // a closure captures "conn", it will send messages to different network connections
		conn.Write([]byte(fmt.Sprint("int subscriber: ", i)))
	})
	ps.Sub(pubsub.NewWrap(f)) // subscribe with a wrapper
	...
}