private static void getCertificates(IoTDAClient client)
        {
            ListCertificatesRequest req = new ListCertificatesRequest
            {
                InstanceId = "1a7ffc5c-d89c-44dd-8265-b1653d951ce0",
            };

            try
            {
                var resp = client.ListCertificates(req);
                foreach (var Certificate in resp.Certificates)
                {
                    Console.WriteLine(JsonConvert.SerializeObject(Certificate));
                }
                Console.WriteLine(resp.Page);
                Console.WriteLine(resp.HttpStatusCode);
            }
            catch (RequestTimeoutException requestTimeoutException)
            {
                Console.WriteLine(requestTimeoutException.ErrorMessage);
            }
            catch (ServiceResponseException clientRequestException)
            {
                Console.WriteLine(clientRequestException.HttpStatusCode);
                Console.WriteLine(clientRequestException.ErrorCode);
                Console.WriteLine(clientRequestException.ErrorMsg);
            }
            catch (ConnectionException connectionException)
            {
                Console.WriteLine(connectionException.ErrorMessage);
            }
        }