def update_obj(sender, instance, created, **kwargs):
    try:
        site.get_provider(instance)
        site.remove_object(instance)
        site.store_object(instance)
    except UnknownObjectException:
        pass
def remove_obj(sender, instance, **kwargs):
    try:
        site.get_provider(instance)
        site.remove_object(instance)
    except UnknownObjectException:
        pass