code: def test_mp_dataset(self):
      print("persistent", dist.get_rank())
      items = [[list(range(i))] for i in range(5)]
      cache_dir = os.path.join(self.tempdir, "test")
      ds = PersistentDataset(
          items, transform=_InplaceXform(), cache_dir=cache_dir
      )
      self.assertEqual(
          items, [[[]], [[0]], [[0, 1]], [[0, 1, 2]], [[0, 1, 2, 3]]]
      )
      ds1 = PersistentDataset(
          items, transform=_InplaceXform(), cache_dir=cache_dir
      )
      self.assertEqual(list(ds1), list(ds))
      self.assertEqual(
          items, [[[]], [[0]], [[0, 1]], [[0, 1, 2]], [[0, 1, 2, 3]]]
      )
  
imports: from __future__ import annotations
  import os
  import shutil
  import tempfile
  import unittest
  import numpy
  import torch.distributed
  from monai.data import PersistentDataset, json_hashing
  from monai.transforms import Transform
  from tests.utils import DistCall, DistTestCase
label_desc: Use image node_id 3 for calling the TestDistCreateDataset obj's underlying member method code with example usage: obj.test_mp_dataset() without return types