Returns all objects that are attached to given model

def for_model(self, model, content_type=None):
        ''' Returns all objects that are attached to given model '''
        content_type = content_type or ContentType.objects.get_for_model(model)
        kwargs = {
                    self.ct_field: content_type,
                    self.fk_field: model.pk
                 }
        objects = self.get_query_set().filter(**kwargs)
        return objects