code: func FibonacciRetryStrategy(iteration int64) time.Duration {
  	var a, b, i, tmp int64
  	a = 0
  	b = 1
  	for i = 0; i < iteration; i++ {
  		tmp = a + b
  		a = b
  		b = tmp
  	}
  	return time.Duration(a) * time.Second
  }
docs: // FibonacciRetryStrategy waits for an increasing amount of time following the Fibonacci sequence