How to use the ctpwrapper.ApiStructure.QryInvestorField function in ctpwrapper

def OnRspUserLogin(self, pRspUserLogin, pRspInfo, nRequestID, bIsLast):

        if pRspInfo.ErrorID != 0:
            print("Md OnRspUserLogin failed error_id=%s msg:%s",
                  pRspInfo.ErrorID, pRspInfo.ErrorMsg.decode('gbk'))
        else:
            print("Md user login successfully")

            inv = ApiStructure.QryInvestorField(BrokerID=self.broker_id, InvestorID=self.investor_id)

            self.ReqQryInvestor(inv, self.inc_request_id())
            req = ApiStructure.SettlementInfoConfirmField.from_dict({"BrokerID": self.broker_id,
                                                                     "InvestorID": self.investor_id})

            self.ReqSettlementInfoConfirm(req, self.inc_request_id())