23            .HandleResult<HttpResponseMessage>(r => r.StatusCode == HttpStatusCode.TooManyRequests)
 
   24            .WaitAndRetryAsync(retryCount, attempt =>
 
   26                var calculated = (int)Math.Floor(Math.Pow(2, attempt));
 
   27                var backoff = calculated > maxBackoff.Seconds ? maxBackoff.Seconds : calculated;
 
   28                return TimeSpan.FromSeconds(backoff);