[Python] 任意の次元のlistをシャッフルしたい

import random

class ShuffleList:
    def __init__(self, target: list):
        # init
        self._temp_list = []
        self._target = target

    def _unpack(self, _target):
        if isinstance(_target, int):
            # _targetがintなら仮リストに追加
            self._temp_list.append(_target)
            return

        for _elem in _target:
            # そうでなければ、_targetの各要素について再帰
            self._unpack(_elem)
            continue

    def _pack(self, _target):
        if isinstance(_target, int):
            # _targetがintなら仮リストからpop
            return self._temp_list.pop()

        _ret_list = list()
        for _elem in _target:
            # そうでなければ、_targetの各要素について再帰
            ret_list.append(self._pack(_elem))
            continue
        return _ret_list

    def shuffle(self):
        self._unpack(self._target)
        random.shuffle(self._temp_list)
        return self._pack(self._target)

# test 1
gave: [4719, 3584, 8817, 2025, 7029, 6098, 3316, 5953, 8539, 1648]
got : [1648, 8817, 3584, 5953, 6098, 3316, 2025, 8539, 4719, 7029]

# test 2
gave: [1, 2, 3, [4, 5, 6, [7, 8, 9, [10, 11, 12], [13, 14, 15], [16, 17, 18]]]]
got : [10, 3, 2, [13, 7, 4, [16, 18, 15, [5, 14, 6], [11, 12, 9], [17, 8, 1]]]]

My Shuffle
0.26448855400085447 [s]
random.shuffle
0.20115196704864502 [s]