human
Solve the following python programming problem given the following code:
def Transform(self, client, viewpoint, callback) : 
    from activity import Activity 
    from followed import Followed 
    from viewpoint import Viewpoint 
    def _OnQuery(activities_followers) : 
        (activities, (follower_ids, last_key)) = activities_followers 
        with util.Barrier (partial (callback, viewpoint)) as b : 
            old_timestamp = viewpoint.last_updated 
            if (len (activities) > 0) : 
                new_timestamp = max ((a.timestamp for a in activities)) 
else : 
                new_timestamp = 0 
viewpoint.last_updated = new_timestamp 
            self._LogUpdate (viewpoint) 
            for follower_id in follower_ids : 
                logging.info (('Followed (user_id=%s, viewpoint_id=%s): %s => %s' % (follower_id, viewpoint.viewpoint_id, Followed._TruncateToDay (old_timestamp), Followed._TruncateToDay (new_timestamp)))) 
                if Version._mutate_items : 
                    Followed.UpdateDateUpdated (client, follower_id, viewpoint.viewpoint_id, old_timestamp, new_timestamp, b.Callback ()) 
with util.ArrayBarrier (_OnQuery) as b : 
        Activity.RangeQuery (client, viewpoint.viewpoint_id, None, None, None, b.Callback ()) 
        Viewpoint.QueryFollowerIds (viewpoint, viewpoint.viewpoint_id, b.Callback ()) 

    
    

    Fix the buggy line: Viewpoint.QueryFollowerIds (viewpoint, viewpoint.viewpoint_id, b.Callback ())
assistant
#Here is Python program to fix the buggy line: Viewpoint.

Viewpoint.QueryFollowerIds (client, viewpoint.viewpoint_id, b.Callback ())