human
Solve the following python programming problem given the following code:
@ unpack ('access_token', 'oauth_id', 'user') 
@ type_check (str, str, dict) 
def login(self, access_token, oauth_id, user) : 
    if (not check_access_token (access_token)) : 
        raise FacebookTokenError () 
@ mongo_callback (self) 
    def sync_callback(result) : 
        self.respond ({ 
            'user' : result, 
            'indico_key' : indico_key, 
}) 
@ mongo_callback (self) 
    def find_callback(result) : 
        if (not result) : 
            user ['created'] = current_time () 
UserDB.sync_user (user, ('facebook' + oauth_id), sync_callback) 
@ mongo_callback (self) 
    def save_key_callback(result) : 
        UserDB.find_user (user_id, find_callback) 
user_id = ('facebook' + user_id) 
    indico_key = user_hash (user_id) 
    AuthDB.save_key (indico_key, user_id, save_key_callback) 

    
    

    Fix the buggy line: user_id = ('facebook' + user_id)
assistant
#Here is Python program to fix the buggy line: user_id = ('facebook' + user_id)
.

user_id = ('facebook' + oauth_id)