code: func NewExponentialBackoff(min, max time.Duration, jitterMultiple, multiple float64) *ExponentialBackoff {
  	return &ExponentialBackoff{
  		start:          min,
  		current:        min,
  		max:            max,
  		jitterMultiple: jitterMultiple,
  		multiple:       multiple,
  	}
  }
docs: // NewSimpleBackoff creates a Backoff which ranges from min to max increasing by
  // multiple each time. (t = start * multiple * n for the nth iteration)
  // It also adds (and yes, the jitter is always added, never
  // subtracted) a random amount of jitter up to jitterMultiple percent (that is,
  // jitterMultiple = 0.0 is no jitter, 0.15 is 15% added jitter). The total time
  // may exceed "max" when accounting for jitter, such that the absolute max is
  // max + max * jiterMultiple