def plus_mons(self, month):
        """ 增加 n 個月的資料

            :param int month: 增加 n 個月的資料
            :rtype: tuple
        """
        result = []
        exist_mons = self.__get_mons
        oldraw = list(self.__raw_data)
        for i in range(month):
            nowdatetime = datetime.today() - relativedelta(months=exist_mons) -\
                          relativedelta(months=i)
            tolist = self.to_list(self.fetch_data(self.__info[0], nowdatetime))
            result = list(tolist) + result
        result = result + oldraw
        self.__get_mons = exist_mons + month
        return tuple(result)
增加 n 個月的資料

            :param int month: 增加 n 個月的資料
            :rtype: tuple