main.go

package main

import (
	"fmt"
	"strings"
)

func main() {
	wisdomPipe := make(chan string)
	mantraPipe := make(chan string)
	echoPipe := make(chan string)
	donePipe := make(chan struct{})
	defer close(donePipe)

	go func(done <-chan struct{}, in <-chan string, out chan string) {
		defer close(wisdomPipe)
		for wiseWords := range in {
			select {
			case out <- wiseWords:
				fmt.Println(wiseWords)
			case <-done:
				return
			}

		}
	}(donePipe, wisdomPipe, mantraPipe)

	go func(done <-chan struct{}, in <-chan string, out chan string) {
		defer close(mantraPipe)
		for mantra := range in {
			select {
			case out <- strings.ToUpper(mantra):
			case <-done:
				return
			}
		}
	}(donePipe, mantraPipe, echoPipe)

	go func(done <-chan struct{}, in <-chan string) {
		defer close(echoPipe)
		for echo := range in {
			select {
			case <-done:
				return
			default:
				fmt.Println(echo)
			}
		}
	}(donePipe, echoPipe)

	wordsOfWisdom := []string{
		"Do not communicate by sharing memory;",
		"instead, share memory by communicating.",
	}
	
	for _, words := range wordsOfWisdom {
		wisdomPipe <- words
	}
}