用Python写一个批量生成账号的函数（用户控制数据长度、数据条数）

# 1、写一个函数，批量生成一些注册使用的账号：产生的账号是以@163.com结尾，长度由用户输入，产生多少条也由用户输入，用户名不能重复，用户名必须由大写字母、小写字母、数字组成

import random,string
def Users(num,len):
    result = []
    a = string.ascii_lowercase
    b = string.ascii_uppercase
    c = string.digits
    d = string.ascii_letters
    count = 0
    while count < num:
        if len > 2:
            a1 = random.choice(a)
            b1 = random.choice(b)
            c1 = random.choice(c)
            d1 = random.sample(d,len-3)
            d1.append(a1)
            d1.append(b1)
            d1.append(c1)
            random.shuffle(d1)
            users = ''.join(d1) + '@163.com' +'
'
            if users not in result:
                result.append(users)
                count +=1
        else:
            print('请输入大于2的长度')
            break
    with open('users.txt','w') as fw:
        fw.writelines(result)
Users(1,3)

#用集合的方式实现
def USERS(num,len):
    result = []
    all_str = string.ascii_letters + string.digits
    upp_str = string.ascii_uppercase
    low_str = string.ascii_lowercase
    str = set(string.digits)
    count = 0
    while count < num:
        if len > 2:
            res = random.sample(all_str,len)
            if set(res) & set(upp_str) and set(res) & set(low_str) and set(res) & str:
                user = ''.join(res) + '@163.com' + '
'
                if user not in result:
                    result.append(user)
                    count +=1
        else:
            print('请输入大于2的长度！')
            break
    with open('users.txt','w') as fw:
        fw.writelines(result)
USERS(3,3)