class User(object):
    def __init__(self, id, username, password):
        self.id = id
        self.username = username
        self.password = password
 
    def __str__(self):
        return "User(id='%s')" % self.id
 
user = User(1, 'user', 'password')
def authenticate(username, password):
    if username == user.username and password == user.password:
        return user
 
def identity(payload):
    return user