code: def __init__(self, dataset_key_dir: str):
      self._path = os.path.join(dataset_key_dir, _METADATA_FILE_NAME)
  
imports: import os
  import pickle
  import re
  import sys
  from typing import Iterable, Mapping, List, Optional, Union, Tuple
  import apache_beam
  import tensorflow
  from tfx_bsl.types import tfx_namedtuple
label_desc: Use image node_id 1 to create a new _WriteMetadata object from inherited base classes: beam with example: obj = _WriteMetadata(dataset_key_dir)