TrackTime use defer

func TrackTime(pre time.Time) time.Duration {
    elapsed := time.Since(pre)
    fmt.Println("time elapsed: ", elapsed)
    return elapsed

}

func main() {
    defer TrackTime(time.Now())
    time.Sleep(3 * time.Second)
}

or

func TrackTime() func() {
    pre := time.Now()
    return func() {
       elapsed := time.Since(pre)
       fmt.Println("time elapsed: ", elapsed)
    }
}

func main() {
    defer TrackTime()()
    time.Sleep(3 * time.Second)

}