package main

import (
    "fmt"
    "time"
    )

func goroutine(ch chan<- string) {
    time.Sleep(time.Second * 1)
    ch <- "done"
}

func main() {
    buffer := 3
    ch := make(chan string, buffer)
    
    go goroutine(ch)
    go goroutine(ch)
    go goroutine(ch)

    // wait for all goroutines to finish
    for len(ch) < buffer {        
    }

    close(ch)

    fmt.Println("Done")
}