public Task<Subscription> GetSubscriptionAsync(string SubscriptionId)
{
string[] args = new string[] { cspApiUrl, reseller_id, SubscriptionId };
string uri = string.Format("{0}/{1}/subscriptions/{2}", args);
APIService service = new APIService(uri);
service.Request.Headers.Add("api-version", "2015-03-31");
service.Request.Headers.Add("x-ms-correlation-id", Guid.NewGuid().ToString());
service.Request.Headers.Add("Authorization", "Bearer " + sa_token.access_token);
return service.GetAsync<Subscription>();
}