private async void Button_Click_1(object sender, RoutedEventArgs e)
        {
            Windows.Web.Http.HttpClient client = new Windows.Web.Http.HttpClient();
            IInputStream inputStream           = await client.GetInputStreamAsync(new Uri(txtUrl.Text, UriKind.Absolute));

            Stream         webStream = inputStream.AsStreamForRead();
            FileSavePicker picker    = new FileSavePicker();

            picker.FileTypeChoices.Add("Text", new List <string>()
            {
                ".txt", ".html"
            });
            picker.FileTypeChoices.Add("Binary", new List <string>()
            {
                ".txt", ".dat"
            });
            StorageFile file = await picker.PickSaveFileAsync();

            Stream fileStream = await file.OpenStreamForWriteAsync();

            await webStream.CopyToAsync(fileStream);

            await new MessageDialog("File Saved").ShowAsync();
        }