'Return list of which class names have objects
referencing this one.
passable_classes means classes to ignore.'

def get_dependencies(self, passable_classes=[]):

    class_names = []
    for related_object in (self._meta.get_all_related_objects() + self._meta.get_all_related_many_to_many_objects()):
        manager = getattr(self, related_object.get_accessor_name())
        model = getattr(manager, 'model')
        if manager.all():
            class_names.append(model.__name__)
    return (set(class_names) - set(passable_classes))
