private void button_Clicked(object sender, EventArgs e)
 {
     game.SetButton((Button)sender);
     if (game.CheckWinner(buttons))
     {
         ITextToSpeech speech = DependencyService.Get <ITextToSpeech>();
         if (speech != null)
         {
             speech.Speak("Game over");
         }
         GameOverStackLayout.IsVisible = true;
     }
 }