Python定义函数

Python定义函数完成表达式1-1/2+1/3-1/4+……+1/99-1/100+……+1/(n-1)-1/n的值并输出。友友们帮忙看看

def fun(n):
    res = 0
    sign = 1
    for i in range(1,n+1):
        res += sign*1/i
        sign *= -1
    return res

print(fun(5))