code: def get_history(self, start, end):
          
          return self.history_table.set_index(
              'datetime',
              drop=False
          ).loc[slice(pd.Timestamp(start),
                      pd.Timestamp(end))]
docs: 返回历史成交
  
          Arguments:
              start {str} -- [description]
              end {str]} -- [description]