private async void TokenButton_OnClicked(object sender, EventArgs e)
 {
     TokenHandler th = new TokenHandler();
     string token = await th.GetToken();
     TextBox.Text = token;
 }
 private async void DeviceIdButton_OnClicked(object sender, EventArgs e)
 {
     TokenHandler th = new TokenHandler();
     string deviceId = await th.GetDeviceId();
     TextBox.Text = deviceId;
 }