编写一个登陆接口

要求：
1、输入用户名密码
2、认证成功后显示欢迎信息
3、输错三次后锁定
# -*- coding:utf-8 -*- 
import re 
count=1 
success=0 
username = raw_input("Please input username:") 
for content in open('C:\Users\Administrator.SKY-20140501YNV\Desktop\dataset.txt'): 
    username_code = re.split(':', content)
    content_username = username_code[0] 
    if username==content_username:
         break
 else:
     print "Your user dosen't exit"
     count=4 for line in open('C:\Users\Administrator.SKY-20140501YNV\Desktop\lockfile.txt'):
     line=line.rstrip('\n')
     if username==line:
         count=4
         print "Your user has been locked!" 
        break
 while count<4:
     code=raw_input("Please input code:")
     for content in open('C:\Users\Administrator.SKY-20140501YNV\Desktop\dataset.txt'): 
        username_code=re.split(':',content)
         content_username=username_code[0]
         content_code=username_code[1]
         content_code=content_code.rstrip('\n')
         if content_username==username:
             if content_code==code:
                 print "Welcome to new world!"
                 success=1
                 break
             else: 
                print "Mismatch between code and username!"
     count+=1
     if success==1:
         break
     if count==4:
         print "Yours user has been locked!"
         lockfile=open('C:\Users\Administrator.SKY-20140501YNV\Desktop\lockfile.txt','a')
         lockfile.write('\n')
         lockfile.write(username)
         lockfile.close()