code: func newRetryTimer(unit time.Duration, cap time.Duration, doneCh chan struct{}) <-chan int {
  	return newRetryTimerWithJitter(unit, cap, MaxJitter, doneCh)
  }
docs: // newRetryTimer creates a timer with exponentially increasing delays
  // until the maximum retry attempts are reached. - this function provides
  // resulting retry values to be of maximum jitter.