Let me explain:
For basic keyboard, there are "lower case abc keyboard", "upper case abc keyboard", "123 keyboard without alt", "123 keyboard with alt". In this case, if you send a alphabet key, it would see if the current keyboard have "self._alpha_key". If not, it means we are good and we are either in lower case abc keyboard or upper case one. If you see _alpha_key, you should tap on it to switch back to alphabetic keyboard.