package main

import "fmt"

func main() {
	ch1 := make(chan int, 3)
	go func() {
		ch1 <- 0
		ch1 <- 1
		ch1 <- 2
		close(ch1)
	}()

	ch2 := make(chan int, 3)
	go func() {
		ch2 <- 10
		ch2 <- 11
		ch2 <- 12
		close(ch2)
	}()

	ch := ch1
	for v := range ch {
		fmt.Println(v)
		ch = ch2
	}
}