human
Solve the following python programming problem given the following code:
def _get_current_user(self, callback) : 
    "
        An async method to load the current user object.
        The callback  function will receive the current user object or None
        as the parameter 'user'.
        " 
    user_id = self.get_secure_cookie ('user') 
    if (not user_id) : 
        logging.warning ('Cookie not found') 
        callback (user = None) 
        return 
def query_callback(result) : 
        if ((result == 'null') or (not result)) : 
            logging.warning ('User not found') 
            user = { 
                
} 
else : 
            user = tornado.escape.json_decode (result) 
self._current_user = user 
        callback (user = user) 
self.application.client.get (('user:' + user_id), user_id) 
    return 

    
    

    Fix the buggy line: self.application.client.get (('user:' + user_id), user_id)
assistant
#Here is Python program to fix the buggy line: self.

self.application.client.get (('user:' + user_id), def query_callback()