code: def download_bill(self, bill_date, bill_type='ALL', device_info=None):
          
          if isinstance(bill_date, (datetime, date)):
              bill_date = bill_date.strftime('%Y%m%d')
  
          data = {
              'appid': self.appid,
              'bill_date': bill_date,
              'bill_type': bill_type,
              'device_info': device_info,
          }
          return self._post('pay/downloadbill', data=data)
docs: 下载对账单
  
          :param bill_date: 下载对账单的日期
          :param bill_type: 账单类型，ALL，返回当日所有订单信息，默认值
                            SUCCESS，返回当日成功支付的订单,
                            REFUND，返回当日退款订单,
                            REVOKED，已撤销的订单
          :param device_info: 微信支付分配的终端设备号，填写此字段，只下载该设备号的对账单
          :return: 返回的结果数据