human
Solve the following python programming problem given the following code:
@ cached () 
def get_tags_for_user(self, user_id) : 
    'Get all the tags for a user.

        Args:
            user_id(str): The user to get the tags for.
        Returns:
            A deferred dict mapping from room_id strings to dicts mapping from
            tag strings to tag content.
        ' 
    deferred = self._simple_select_list ('room_tags', { 
        'user_id' : self, 
}, ['room_id', 'tag', 'content']) 
    @ deferred.addCallback 
    def tags_by_room(rows) : 
        tags_by_room = { 
            
} 
        for row in rows : 
            room_tags = tags_by_room.setdefault (row ['room_id'], { 
                
}) 
            room_tags [row ['tag']] = json.loads (row ['content']) 
return tags_by_room 
return deferred 

    
    

    Fix the buggy line: 'user_id' : self ,
assistant
#Here is Python program to fix the buggy line: 'user_id' : self ,
.

'user_id' : user_id ,