对如下嵌套列表中的元素进行求和

code：

def nested_sum(ls):
    sum=0
    for item in ls:
        if isinstance(item,list):
            sum+=nested_sum(item)
        else:
            sum+=item
    return sum

if __name__ == '__main__':
    l1=list(range(100))
    print(nested_sum(l1))
    l2=[[1,2],3,[4,5,6]]
    print(nested_sum(l2))
    l3=[[1,2],[3],[4,5,6]]
    print(nested_sum(l3))
    l4=[1,2,[3],[4,5,6]]
    print(nested_sum(l4))
    l5=[[1,2],[3],[4,5,6]]
    print(nested_sum(l5))
    l6=[[1,2],[3],[4,5,6],[[7,8],9]]
    print(nested_sum(l6))
    l7=[[1,2],[3],[4,5,6],[[7,8],[9]]]
    nested_sum(l7)
    print(nested_sum(l7))

结果：

end