python 用户登录程序

需求：
让用户输入用户名密码
认证成功后显示欢迎信息
输错三次后退出程序
可以支持多个用户登录 
用户3次认证失败后，退出程序，再次启动程序尝试登录时，还是锁定状态

# -*- coding:utf-8 -*-
# author: Skyell
flag = True
account_list = {'xiaopang': '123', 'haohao': '234'}   # 已有账号、密码
username = input('Please input your username:').strip()
lock_name = open('lockname_list.txt', 'r', encoding="utf-8")
for i in lock_name:
    lockname = i.strip()
    if lockname == username:
        print('your account has been locked!')
        break
    else:
        continue
lock_name.close()
if username != lockname:
    password_wrong = 0
    while flag:
        password = input('Please input your password:').strip()
        acc_name = [keys for keys in account_list]  # 利用列表生成式将账号信息存入列表中
        if username in acc_name:
            if account_list[username] == password:  # 判断账号、密码是否正确
                print('welcome back!')
                flag = False
                break
            else:
                print('Please try again!')
                password_wrong += 1
                if password_wrong == 3:           # 密码错误3次，锁定用户
                    print('your account has been locked')
                    lock_name = open('lockname_list.txt', 'a+', encoding="utf-8")
                    lock_name.write(username+'
')          # 将被锁定的账号写入锁定文件中
                    lock_name.close()
        else:
            print('Account is not found')
            flag = False
            break

基本实现需求，继续继续！