用户登陆接口，输错3次限制登陆

# _*_coding:utf-8_*_
# Author:len liu

'''
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
'''

user_list = {
    "len":'aaa',
    "alen":'bbb',
    "blen":'ccc'
}
count = 0
while True:
    user_input = input("pls input username:")
    passwd_input = input("pls input password:")

    if user_input not in user_list:
        print("no this user")
        continue
    with open('black_list.txt','r') as f:
        lock_user=f.read().split(',')
        #print(lock_user)
        if user_input in lock_user:
            print('your count %s locked!'%user_input)
            break

    if user_input in user_list and passwd_input == user_list[user_input]:
        print("login sucessful!")
        break
    else:
        print("invaild username or password")
        count +=1
        if count >2 :
            with open('black_list.txt','a') as f:
                f.write(user_input +',')
            print("your count try too times ,locked!")
            break