def _prune_subdirs(dir_: str) -> None:
    """
    Delete all subdirs in training log dirs.

    :param dir_: dir with training log dirs
    """
    for logdir in [path.join(dir_, f) for f in listdir(dir_) if is_train_dir(path.join(dir_, f))]:
        for subdir in [path.join(logdir, f) for f in listdir(logdir) if path.isdir(path.join(logdir, f))]:
            _safe_rmtree(subdir)
Delete all subdirs in training log dirs.

    :param dir_: dir with training log dirs