package main
import (
"fmt"
"time"
)
func double(num int, ch chan int) {
time.Sleep(time.Second * 1)
ch <- num * 2
}
func main() {
// var ch chan int = make(chan int)
ch := make(chan int)
fmt.Println("Start!")
go double(10, ch)
time.Sleep(time.Second * 3)
fmt.Println("Finish!")
}