A retry function in Golang

retry.go

func retry(attempts int, sleep time.Duration, f func() error) (err error) {
    for i := 0; i < attempts; i++ {
        if i > 0 {
            log.Println("retrying after error:", err)
            time.Sleep(sleep)
            sleep *= 2
        }
        err = f()
        if err == nil {
            return nil
        }
    }
    return fmt.Errorf("after %d attempts, last error: %s", attempts, err)
}