Converts this object to its json representation following the Telegram API guidelines described here:
        https://core.telegram.org/bots/api#replykeyboardmarkup
        :return:

def to_json(self):
        """
        Converts this object to its json representation following the Telegram API guidelines described here:
        https://core.telegram.org/bots/api#replykeyboardmarkup
        :return:
        """
        json_dict = {'keyboard': self.keyboard}
        if self.one_time_keyboard:
            json_dict['one_time_keyboard'] = True

        if self.resize_keyboard:
            json_dict['resize_keyboard'] = True

        if self.selective:
            json_dict['selective'] = True

        return json.dumps(json_dict)