Go playground: run Go in your browser, goroutines and channels included

package main

import "fmt"

func main() {
	fmt.Println("Hello, world!")
	fmt.Println("Learn to code")
	fmt.Println("by playing.")
	msg := "unlocked!"
	for n := 1; n <= 3; n++ {
		fmt.Println("Level", n, msg)
	}
}