package main
import (
	"fmt"
	"sync"
	"time"
)
func () {
	var mu sync.Mutex
	go func() {
		fmt.Println(1, "prepare lock")
		mu.Lock()
		fmt.Println(1, "locked, sleeping 2s")
		time.Sleep(2e9)
		mu.Unlock()
		fmt.Println(1, "unlocked")
	}()
	go func() {
        fmt.Println(2, "prepare lock")
		mu.Lock()
		fmt.Println(2, "locked, sleeping 1s")
		time.Sleep(1e9)
		mu.Unlock()
		fmt.Println(2, "unlocked")
	}()
	time.Sleep(4e9)
}