code: def _save(self, hash_key, obj):
      if self.in_memory:
          _data_mem_cache.ttl(
              key=hash_key, value=copy.deepcopy(obj), ttl=self.ttl
          )
      else:
          os.makedirs(_cache_path, exist_ok=True)
  
          cached_file = os.path.join(_cache_path, f"{hash_key}.tmp")
          torch.save(obj, cached_file)
          _data_file_cache.add_session(
              cached_file, expiry=self.ttl, session_id=hash_key
          )
  
imports: import copy
  import logging
  import os
  import pathlib
  from typing import Hashable, Sequence, Tuple, Union
  import torch
  from expiring_dict import ExpiringDict
  from monai.config import KeysCollection
  from monai.data import MetaTensor
  from monai.transforms import Transform
  from monai.utils import ensure_tuple
  from monailabel.utils.others.generic import md5_digest
  from monailabel.utils.sessions import Sessions
label_desc: Use image node_id 6 for calling the CacheTransformDatad obj's underlying member method code with example usage: obj._save(hash_key, obj) without return types