code: def moving_average_bias_ratio(self, date1, date2):
          
          data1 = self.moving_average(date1)[0]
          data2 = self.moving_average(date2)[0]
          cal_list = []
          for i in range(1, min(len(data1), len(data2)) + 1):
              cal_list.append(data1[-i] - data2[-i])
          cal_list.reverse()
          cont = self.__cal_continue(cal_list)
          return cal_list, cont
docs: 計算乖離率（均價）
              date1 - date2
  
              :param int data1: n 日
              :param int data2: m 日
              :rtype: tuple (序列 舊→新, 持續天數)