public static string InvokeApi(string url)
        {
            using(HttpClient client=new HttpClient())
            {
                HttpRequestMessage message = new HttpRequestMessage();
                message.Method = HttpMethod.Get;
                message.RequestUri = new Uri(url);
                var result = client.SendAsync(message).Result;
                string content = result.Content.ReadAsStringAsync().Result;
                return content;
            }
        }