def METHOD_NAME(bm_name: str, target_dir: Path=None) -> str:
    if target_dir is None:
        target_dir = get_output_dir(bm_name)
    fname = "metrics-{}.json".format(datetime.fromtimestamp(time.time()).strftime("%Y%m%d%H%M%S"))
    full_fname = os.path.join(target_dir, fname)
    return full_fname