下面程序的输出结果是为什么是None(语言-python)

def main():
print(min(5，6))

def min(n1，n2):
smallest = n1
if n2 ＜ smallest:
smallest = n2
main()

def main():
    print(min(5，6))

def min(n1，n2):
    smallest = n1
    if n2 ＜ smallest:
        smallest = n2
    return smallest 
main()

min 函数里要 return smallest 才行 ，否则默认返回None