code: def expand(
      self, pipeline: beam.Pipeline
  ) -> beam.PCollection[DatasetCacheMetadata]:
      if tf.io.gfile.glob(self._cache_metadata_path):
          return (
              pipeline
              | "ReadMetadata"
              >> beam.io.ReadFromTFRecord(
                  self._cache_metadata_path, validate=False
              )
              | "Decode" >> beam.Map(DatasetCacheMetadata.decode)
          )
  
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 2 for calling the _ReadMetadata obj's underlying member method code with example usage: obj.expand(pipeline) and returns: unknown