human
Solve the following python programming problem given the following code:
@ classmethod 
def QueryByUser(cls, client, callback, user_id, include_expired = False, include_history = False) : 
    'Returns a list of Subscription objects for the given user.

    By default only includes currently-active subscriptions, and only
    one transaction per subscription.  To return expired subscriptions,
    pass include_expired=True.  To return all transactions (even those
    superceded by a renewal transaction for the same subscription),
    pass include_history=True (which implies include_expired=True).
    ' 
    history_results = [] 
    latest = { 
        
} 
    def _VisitSub(sub, callback) : 
        if include_history : 
            history_results.append (sub) 
else : 
            if ((sub.expiration_ts < time.time ()) and (not include_expired)) : 
                callback () 
                return 
if ((sub.subscription_id in latest) and (latest [sub.subscription_id].timestamp > sub.timestamp)) : 
                callback () 
                return 
latest [sub.subscription_id] = sub 
callback () 
def _OnVisitDone() : 
        if include_history : 
            assert (not latest) 
            callback (history_results) 
else : 
            assert (not history_results) 
            callback (latest.values ()) 
Subscription.VisitRange (client, user_id, None, None, latest, _OnVisitDone) 

    
    

    Fix the buggy line: Subscription.VisitRange (client, user_id, None, None, latest, _OnVisitDone)
assistant
#Here is Python program to fix the buggy line: Subscription.

Subscription.VisitRange (client, user_id, None, None, def _VisitSub(, _OnVisitDone)