main.go

package main

import (
	"fmt"
	"time"
)

func main() {
	var (
		ch  = make(chan int)
		out = make(chan int)
	)

	go server(ch)
	go worker(ch, out)
	go notify(out)

	time.Sleep(5 * time.Second)

	close(ch)
	close(out)
}

func server(ch chan<- int) {
	for i := range 10 {
		ch <- i
	}
}

func worker(in <-chan int, out chan<- int) {
	for i := range in {
		out <- i
	}
}

func notify(out <-chan int) {
	for i := range out {
		fmt.Println(i)
	}
}