code: func (totp *TOTP) FromNow(periods int64) int32 {
  	period := (time.Now().Unix() / int64(totp.Period)) + int64(periods)
  	return totp.ForPeriod(period)
  }
docs: // Return the Time Based One Time Password for the time-period
  // that is Now + the given periods.
  // This is useful if you want to provide some flexibility around the acceptance
  // of codes.
  // For instance, you might want to accept a code that is valid in the current
  // period (FromNow(0)), or that was valid in the previous period (FromNow(-1)) or that
  // will be valid in the next period (FromNow(1)).
  // This means that every code is therefore valid for 3 * totp.Period.