A Fibonacci data cal in Golang goroutine and channel

fib.go

package main

import (
	"fmt"
)

func shower(c chan int, quit chan bool) {
	for {
		select {
		case j := <-c:
			fmt.Printf("%v ", j)
		case <-quit:
			break
		}
	}
}

func dup3(in <-chan int) (<-chan int, <-chan int, <-chan int) {
	a, b, c := make(chan int, 2), make(chan int, 2), make(chan int, 2)
	go func() {
		for {
			println("pop x")
			x := <-in
			println("push a ", x)
			a <- x
			println("push b ", x)
			b <- x
			println("push out ", x)
			c <- x
		}
	}()
	return a, b, c
}

func fib() <-chan int {
	x := make(chan int, 2)
	a, b, out := dup3(x)
	go func() {
		println("push x 0")
		x <- 0
		println("push x 1")
		x <- 1
		println("pop a")
		<-a
		for {
			println("get a + b then push x ")
			x <- <-a + <-b
		}
	}()
	return out
}

func main() {
	// ch := make(chan int)
	// quit := make(chan bool)
	// go shower(ch, quit)
	// for i := 0; i < 10; i++ {
	// 	ch <- i
	// }
	// quit <- false
	x := fib()
	for i := 0; i < 10; i++ {
		println("pop out")
		fmt.Printf("%v ", <-x)
	}
}