human
Solve the following python programming problem given the following code:
def create_manager(self, instance, superclass) : 
    '
        Dynamically create a RelatedManager to handle the back side of the (G)FK
        ' 
    rel_model = superclass.rating_model 
    rated_model = self.rated_model 
    class RelatedManager (superclass) : 
        def get_query_set(self) : 
            qs = RatingsQuerySet (rel_model, rated_model = rated_model) 
            return qs.filter (** self.core_filters) 
def add(self, * objs) : 
            lookup_kwargs = rel_model.lookup_kwargs (instance) 
            for obj in objs : 
                if (not isinstance (obj, self.model)) : 
                    raise TypeError (("'%s' instance expected" % self.model._meta.object_name)) 
for (k, v) in lookup_kwargs.iteritems () : 
                    setattr (obj, k, v) 
obj.save () 
add.alters_data = True 
        def create(self, **kwargs) : 
            kwargs.update (rel_model.lookup_kwargs (instance)) 
            return super (RelatedManager, self).create (** kwargs) 
create.alters_data = True 
        def get_or_create(self, **kwargs) : 
            kwargs.update (rel_model.lookup_kwargs (instance)) 
            return super (RelatedManager, self).get_or_create (** kwargs) 
get_or_create.alters_data = True 
        def remove(self, * objs) : 
            for obj in objs : 
                if (obj in self.all ()) : 
                    obj.delete () 
else : 
                    raise rel_model.DoesNotExist (('%r is not related to %r.' % (obj, instance))) 
remove.alters_data = True 
        def clear(self) : 
            self.all ().delete () 
clear.alters_data = True 
        def rate(self, user, score) : 
            (rating, created) = self.get_or_create (user = user) 
            if (created or (score != rating.score)) : 
                rating.score = score 
                rating.save () 
return rating 
def unrate(self, user) : 
            return self.filter (user = user, ** rel_model.lookup_kwargs (instance)).delete () 
def perform_aggregation(self, aggregator) : 
            score =...

    
    

    Fix the buggy line: rel_model = superclass.rating_model
assistant
#Here is Python program to fix the buggy line: rel_model = superclass.

rel_model = self.rating_model