Python给你一个字符串，你怎么判断是不是ipv4地址？手写这段代码，并写出测试用例【杭州多测师_王sir】

import re

def check_ip(one_str):

    compile_ip = re.compile('^(([1-9]|[1-9]\d|1\d{2}|2[0-4]\d|25[0-5])\.){3}(\d|[1-9]\d|1\d{2}|2[0-4]\d|25[0-5])$')
    if compile_ip.match(one_str):
        return True
    else:
        return False

if __name__ == '__main__':

    ip_list = ['', '172.31.137.251', '100.10.0.1000', '1.1.1.1', '12.23.13', 'aa.12.1.2', '12345678', '289043jdhjkbh']

    for one_str in ip_list:
    
if check_ip(one_str): 
            print('{0} is a legal ip address!'.format(one_str))
        else:
            print('{0} is not a legal ip address!'.format(one_str))

def check_ip(one_str):

    if '.' not in one_str:
        return False
    elif one_str.count('.') != 3:
        return False
    else:
        flag = True
        one_list = one_str.split('.')
        for one in one_list:
            try:
                one_num = int(one)
                if one_num >= 0 and one_num <= 255:
                    pass
                else:
                    flag = False
            except:
                flag = False
        return flag

if __name__ == '__main__':

    ip_list = ['', '172.31.137.251', '100.10.0.1000', '1.1.1.1', '12.23.13', 'aa.12.1.2', '12345678', '289043jdhjkbh']

    for one_str in ip_list:
        if check_ip(one_str):  #字符串方法
            print('{0} is a legal ip address!'.format(one_str))
        else:
            print('{0} is not a legal ip address!'.format(one_str))