编写用户登录界面---if语句

#!/usr/bin/env python

# -*- coding: utf-8 -*-
import getpass
_username = 'tom'
_password = '123'
username = input("username:")
password = getpass.getpass("password：")
if _username == username and _password == password:
  print("welcom user {name} login ...".format(name = username))
else:
  print("Invalid username or password!")