template<class ItemType>
BinaryNode < ItemType >* BinaryNodeTree<ItemType>::removeValue (BinaryNode < ItemType > *subTreePtr, const ItemType target, bool & success)
{
    if(subTreePtr == nullptr) //null thi thoat
        return subTreePtr;

    if (subTreePtr->getItem() == target) // da tim thay
    {
        subTreePtr = moveValuesUpTree(subTreePtr);
        success = true;
        return subTreePtr;
    }
    else
    {
        auto targetNodePtr = removeValue(subTreePtr->getLeftChildPtr(), target, success);
        subTreePtr->setLeftChildPtr(targetNodePtr);
        if (!success) //tim ben phai neu ben trai k co
        {
            targetNodePtr = removeValue(subTreePtr->getRightChildPtr(), target, success);
            subTreePtr->setRightChildPtr(targetNodePtr);
        }  // end if

        return subTreePtr;
    }  // end if
}  // end removeValue