def METHOD_NAME(self, src: PathLike, key: t.Optional[str] = None) -> None:
    """
    Link a file to the object store. only support hard link for now.
    Args:
        src: the file links from
        key: the hash of the file, if not provided, will be calculated
    """
    file = BlakeFile(src, key)
    dst = Path(self.root) / file.hash[:2] / file.hash
    if dst.exists():
        return
    try:
        file.METHOD_NAME(dst)
    except FileExistsError:
        pass