取前几个周期的Ref函数

def Ref(contract,pricetype,bartype,steps):

#引用X在N个周期前的值
#例:REF(CLOSE,5);表示引用当前周期前第5个周期的收盘价

option = PBObj()
#option.StartDate = 
option.EndDate = GetCurrentTime()
option.Count=steps+1
klinedata = GetHisData(contract , bartype, option) #bartype like BarType.Min

if len(klinedata)>0:
    if pricetype=="close": #取收盘价

        print("checking----- "+str(klinedata[(steps+1)*-1].close)+" "+str(klinedata[(steps+1)*-1].datetime))

        return klinedata[(steps+1)*-1].close

else:
    print("数据不全，未查到数据")
    return 0