python3 验证用户名密码

输入用户名，密码，匹配通过，不匹配报错

import getpass

user = input('input username: ')
pwd = getpass.getpass('input password: ')

if user == 'xp' and pwd == 'xp0001':
    print("welcome %s" % user)
else:
    print("Error username or password")

增加计数，大于3次报错

import getpass
user_info = {}

a = {'xp':{'pwd':'xp0001','block':0}}

count = a.get('xp')['block']
print(count)
while count < 3:
    user = input('input username: ')
    pwd = getpass.getpass('input password: ')

    if user == 'xp' and pwd == 'xp0001':
        print("welcome %s" % user)
        break
    else:
        print("Error username or password,retry")

    count += 1
else:
    print("%s is locked" % user)
    a['xp']['block'] = 3

可是这样再执行的时候，block值还是返回0，增加个文件吧