public static async Task <Account> Login(string email, string password)
        {
            Account account;
            string  jsondata = JsonConvert.SerializeObject(new { Email = email, Password = password });

            try{
                HttpResponseMessage hrm = await httpClient.PostAsync(url + "Login", new StringContent(jsondata, Encoding.UTF8, "application/json"));

                hrm.EnsureSuccessStatusCode();
                string response = await hrm.Content.ReadAsStringAsync();

                SignInResponse signinresponse = JsonConvert.DeserializeObject <SignInResponse>(response);
                account = new Account(email, signinresponse.Token);
                return(account);
            } catch (Exception e) {
                return(null);
            }
        }
        public static async Task <Account> Register(string email, string password, string nativeLanguage)
        {
            Account account;

            try{
                HttpRequestMessage requestMessage = new HttpRequestMessage(HttpMethod.Post, url + "Register");
                var content = JsonConvert.SerializeObject(new { Email = email, Password = password, NativeLanguage = nativeLanguage });
                requestMessage.Content = new StringContent(content, Encoding.UTF8, "application/json");
                HttpResponseMessage hrm = await httpClient.SendAsync(requestMessage);

                hrm.EnsureSuccessStatusCode();
                string response = await hrm.Content.ReadAsStringAsync();

                SignInResponse registerResponse = JsonConvert.DeserializeObject <SignInResponse>(response);
                account = new Account(email, registerResponse.Token);
                return(account);
            } catch (Exception e) {
                return(null);
            }
        }