code: def market_value(self):
          
          if self.account.daily_hold is not None:
              if self.if_fq:
  
                  return (
                      self.market_data.to_qfq().pivot('close').fillna(
                          method='ffill'
                      ) * self.account.daily_hold.apply(abs)
                  ).fillna(method='ffill')
              else:
                  return (
                      self.market_data.pivot('close').fillna(method='ffill') *
                      self.account.daily_hold.apply(abs)
                  ).fillna(method='ffill')
          else:
              return None
docs: 每日每个股票持仓市值表
  
          Returns:
              pd.DataFrame -- 市值表