'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):

    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)
