code: def end_date(self):
          
          if self.start_==None:
              if len(self.time_index_max) > 0:
                  return str(max(self.time_index_max))[0:10]
              else:
                  print(
                      RuntimeWarning(
                          'QAACCOUNT: THIS ACCOUNT DOESNOT HAVE ANY TRADE'
                      )
                  )
          else:
              return self.end_
docs: 账户的交易结束日期(只在回测中使用)
  
          Raises:
              RuntimeWarning -- [description]
  
          Returns:
              [type] -- [description]