code: def testMetaFeatures(self):
      with beam.Pipeline() as pipeline:
          fpls = create_fpls()
  
          metrics = (
              pipeline
              | "CreateTestInput" >> beam.Create(fpls)
              | "WrapFpls" >> beam.Map(wrap_fpl)
              | "ExtractInterestsNum"
              >> meta_feature_extractor.ExtractMetaFeature(
                  get_num_interests
              )
          )
  
          def check_result(got):
              try:
                  self.assertEqual(2, len(got), "got: %s" % got)
                  for res in got:
                      self.assertIn(
                          "num_interests",
                          res[
                              constants.FEATURES_PREDICTIONS_LABELS_KEY
                          ].features,
                      )
                      self.assertEqual(
                          len(
                              meta_feature_extractor.get_feature_value(
                                  res[
                                      constants.FEATURES_PREDICTIONS_LABELS_KEY
                                  ],
                                  "interest",
                              )
                          ),
                          meta_feature_extractor.get_feature_value(
                              res[
                                  constants.FEATURES_PREDICTIONS_LABELS_KEY
                              ],
                              "num_interests",
                          ),
                      )
              except AssertionError as err:
                  raise util.BeamAssertException(err)
  
          util.assert_that(metrics, check_result)
  
file_path: model-analysis/tensorflow_model_analysis/extractors/legacy_meta_feature_extractor_test.py
imports: import apache_beam
  from apache_beam.testing import util
  import numpy
  import tensorflow
  from tensorflow_model_analysis import constants
  from tensorflow_model_analysis.api import types
  from tensorflow_model_analysis.eval_saved_model import testutil
  from tensorflow_model_analysis.extractors import legacy_meta_feature_extractor
  from tensorflow_model_analysis.extractors import slice_key_extractor
  from tensorflow_model_analysis.slicer import slicer_lib
label_desc: Use image node_id 1 for calling the MetaFeatureExtractorTest obj's underlying member method code with example usage: obj.testMetaFeatures() without return types