code: func NewExponentialBackoff(initialTimeout, maxTimeout time.Duration) *ExponentialBackoff {
  	return &ExponentialBackoff{
  		t: float64(int64(initialTimeout / time.Millisecond)),
  		f: 2.0,
  		m: float64(int64(maxTimeout / time.Millisecond)),
  	}
  }
docs: // NewExponentialBackoff returns a ExponentialBackoff backoff policy.
  // Use initialTimeout to set the first/minimal interval
  // and maxTimeout to set the maximum wait interval.