code: def QA_indicator_MFI(DataFrame, N=14):
      
      C = DataFrame['close']
      H = DataFrame['high']
      L = DataFrame['low']
      VOL = DataFrame['volume']
      TYP = (C + H + L) / 3
      V1 = SUM(IF(TYP > REF(TYP, 1), TYP * VOL, 0), N) / \
          SUM(IF(TYP < REF(TYP, 1), TYP * VOL, 0), N)
      mfi = 100 - (100 / (1 + V1))
      DICT = {'MFI': mfi}
  
      return pd.DataFrame(DICT)
docs: 资金指标
      TYP := (HIGH + LOW + CLOSE)/3;
      V1:=SUM(IF(TYP>REF(TYP,1),TYP*VOL,0),N)/SUM(IF(TYP<REF(TYP,1),TYP*VOL,0),N);
      MFI:100-(100/(1+V1));
      赋值: (最高价 + 最低价 + 收盘价)/3
      V1赋值:如果TYP>1日前的TYP,返回TYP*成交量(手),否则返回0的N日累和/如果TYP<1日前的TYP,返回TYP*成交量(手),否则返回0的N日累和
      输出资金流量指标:100-(100/(1+V1))