human
Solve the following python programming problem given the following code:
@ classmethod 
@ gen.coroutine 
def NotifyRemoveFollowers(cls, client, viewpoint_id, existing_followers, remove_ids, act_dict) : 
    'Notifies removed followers that they have been removed from the specified viewpoint.
    Invalidates the viewpoint attributes for those followers so that they will get the REMOVED
    label. Also notifies all existing followers of the viewpoint that they need to reload the
    list of viewpoint followers. Creates a remove_followers activity in the viewpoint.
    ' 
    activity_func = NotificationManager._CreateActivityFunc (act_dict, Activity.CreateRemoveFollowers, remove_ids) 
    remove_id_set = set (remove_ids) 
    def _GetInvalidate(follower_id) : 
        if (follower_id in remove_id_set) : 
            return { 
                'viewpoints' : [{ 
                    'viewpoint_id' : viewpoint_id, 
                    'get_attributes' : True, 
}], 
} 
else : 
            return { 
                'viewpoints' : [{ 
                    'viewpoint_id' : viewpoint_id, 
                    'get_followers' : True, 
}], 
} 
(yield NotificationManager._NotifyFollowers (client, remove_id_set, existing_followers, _GetInvalidate, activity_func, always_notify = True)) 

    
    

    Fix the buggy line: (yield NotificationManager._NotifyFollowers (client, remove_id_set, existing_followers, _GetInvalidate, activity_func, always_notify = True))
assistant
#Here is Python program to fix the buggy line: (yield NotificationManager.

(yield NotificationManager._NotifyFollowers (client, viewpoint_id, existing_followers, _GetInvalidate, activity_func, always_notify = True))