class_docstr: CombineFn to generate MatchStats.
class_docstr_tok: ["CombineFn","to","generate","MatchStats","."]
code: def extract_output(
      self, accumulator: np.ndarray
  ) -> feature_skew_results_pb2.MatchStats:
      return feature_skew_results_pb2.MatchStats(
          base_with_id_count=accumulator[0],
          test_with_id_count=accumulator[1],
          identifiers_count=accumulator[2],
          ids_missing_in_base_count=accumulator[3],
          ids_missing_in_test_count=accumulator[4],
          matching_pairs_count=accumulator[5],
          duplicate_id_count=accumulator[6],
          base_missing_id_count=accumulator[7],
          test_missing_id_count=accumulator[8],
      )
  
imports: from typing import Any, Dict, Iterable, Iterator, List, Optional, Tuple, Union
  import apache_beam
  import farmhash
  import numpy
  import tensorflow
  from tensorflow_data_validation import constants
  from tensorflow_data_validation import types
  from tensorflow_data_validation.utils import artifacts_io_impl
  from tensorflow_data_validation.skew.protos import feature_skew_results_pb2
label_desc: Use image node_id 4 for calling the _MergeMatchStatsFn obj's underlying member method code with example usage: obj.extract_output(accumulator) and returns: feature_skew_results_pb2