human
Solve the following python programming problem given the following code:
@ cached_property 
def related_manager_cls(self) : 
    superclass = self.related.model._default_manager.__class__ 
    rel_field = rel_model.related.field 
    rel_model = self.related.model 
    attname = rel_field.rel.get_related_field ().attname 
    class RelatedManager (superclass) : 
        def __init__(self, instance) : 
            super (RelatedManager, self).__init__ () 
            self.instance = instance 
            self.core_filters = { 
                ('%s__%s' % (rel_field.name, attname)) : getattr (instance, attname), 
} 
            self.model = rel_model 
def get_query_set(self) : 
            try : 
                return self.instance._prefetched_objects_cache [rel_field.related_query_name ()] 
except (AttributeError, KeyError) : 
                db = (self._db or router.db_for_read (self.model, instance = self.instance)) 
                qs = super (RelatedManager, self).get_query_set ().using (db).filter (** self.core_filters) 
                val = getattr (self.instance, attname) 
                if ((val is None) or ((val == '') and connections [db].features.interprets_empty_strings_as_nulls)) : 
                    return qs.filter (pk__in = []) 
qs._known_related_objects = { 
                    rel_field : { 
                        self.instance.pk : self.instance, 
}, 
} 
                return qs 
def get_prefetch_query_set(self, instances) : 
            rel_obj_attr = attrgetter (rel_field.attname) 
            instance_attr = attrgetter (attname) 
            instances_dict = dict (((instance_attr (inst), inst) for inst in instances)) 
            db = (self._db or router.db_for_read (self.model, instance = instances [0])) 
            query = { 
                ('%s__%s__in' % (rel_field.name, attname)) : list (instances_dict), 
} 
            qs = super (RelatedManager, self).get_query_set ().using (db).filter (** query) 
            for rel_obj in qs : 
                instance = instances_dict [rel_obj_attr (rel_obj)] 
                setattr (rel_obj,...

    
    

    Fix the buggy line: rel_field = rel_model.related.field
assistant
#Here is Python program to fix the buggy line: rel_field = rel_model.

rel_field = self.related.field