code: func BackoffExponentialWithJitter(scalar time.Duration, jitterFraction float64) BackoffFunc {
  	return func(attempt uint) time.Duration {
  		return backoffutils.JitterUp(scalar*time.Duration(backoffutils.ExponentBase2(attempt)), jitterFraction)
  	}
  }
docs: // BackoffExponentialWithJitter creates an exponential backoff like
  // BackoffExponential does, but adds jitter.