def shiftDown(self,i):
    currentvalue=self.items[self.indexList[i]]
    currentindex=self.indexList[i]
    while i*2<=self.currentSize:
        mc=self.maxChild(i)
        if currentvalue < self.items[self.indexList[mc]]:
            self.indexList[i]=self.indexList[mc]
            i=mc
        else:
            break
    self.indexList[i]=currentindex