def METHOD_NAME(tag: t.Union[str, Tag], creation_time: t.Optional[datetime] = None):
    creation_time = datetime.now() if creation_time is None else creation_time
    with DummyItem.store.register(tag) as path:
        dummy_fs = fs.open_fs(path)
        dummy_fs.writetext("tag", str(tag))
        dummy_fs.writetext("ctime", creation_time.isoformat())