def METHOD_NAME(trial: FrozenTrial) -> List[int]:
    """Return the list of retried trial numbers with respect to the specified trial.
    Args:
        trial:
            The trial object.
    Returns:
        A list of trial numbers in ascending order of the series of retried trials.
        The first item of the list indicates the original trial which is identical
        to the :func:`~optuna.storages.RetryFailedTrialCallback.retried_trial_number`,
        and the last item is the one right before the specified trial in the retry series.
        If the specified trial is not a retry of any trial, returns an empty list.
    """
    return trial.system_attrs.get("retry_history", [])