code: def save(self, data):
      d = dict(data)
  
      hash_keys = [d[k] for k in self.hash_key if d.get(k)]
      hash_key_prefix = md5_digest("".join(hash_keys))
  
      if len(hash_keys) != len(self.hash_key):
          logger.warning(
              f"Ignore caching; Missing hash keys;  Found: {hash_keys}; Expected: {self.hash_key}"
          )
          return d
  
      # full dictionary
      if not self.keys:
          self._save(f"{hash_key_prefix}", d)
      else:
          for key in self.keys:
              self._save(f"{hash_key_prefix}_{key}", d[key])
      return d
  
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 4 for calling the CacheTransformDatad obj's underlying member method code with example usage: obj.save(data) and returns: d, d