code: def test_enrich_utterance(self):
      # Given
      u = text_to_utterance("a b c d e f")
      builtin_ents = [
          {
              "value": "e",
              "resolved_value": "e",
              "range": {"start": 8, "end": 9},
              "entity_kind": "the_snips_e_entity",
          }
      ]
      custom_ents = [
          {
              "value": "c",
              "resolved_value": "c",
              "range": {"start": 4, "end": 5},
              "entity_kind": "the_c_entity",
          }
      ]
  
      vectorizer = CooccurrenceVectorizer()
      vectorizer._language = "en"
  
      # When
      preprocessed = vectorizer._enrich_utterance(
          u, builtin_ents, custom_ents
      )
  
      # Then
      expected = [
          "a",
          "b",
          "THE_C_ENTITY",
          "d",
          "THE_SNIPS_E_ENTITY",
          "f",
      ]
      self.assertSequenceEqual(expected, preprocessed)
  
imports: from __future__ import unicode_literals
  import io
  from builtins import str, zip, range
  import numpy
  from checksumdir import dirhash
  from mock import patch, MagicMock
  from snips_nlu.common.io_utils import temp_dir
  from snips_nlu.common.utils import json_string
  from snips_nlu.constants import LANGUAGE_EN, STEMS, WORD_CLUSTERS, STOP_WORDS
  from snips_nlu.dataset import Dataset
  from snips_nlu.entity_parser import BuiltinEntityParser, CustomEntityParser
  from snips_nlu.entity_parser.custom_entity_parser_usage import CustomEntityParserUsage
  from snips_nlu.exceptions import _EmptyDatasetUtterancesError
  from snips_nlu.intent_classifier.featurizer import CooccurrenceVectorizer, Featurizer, TfidfVectorizer
  from snips_nlu.intent_classifier.log_reg_classifier_utils import text_to_utterance
  from snips_nlu.pipeline.configs import FeaturizerConfig
  from snips_nlu.pipeline.configs.intent_classifier import CooccurrenceVectorizerConfig, TfidfVectorizerConfig
  from snips_nlu.tests.utils import FixtureTest, get_empty_dataset, EntityParserMock
label_desc: Use image node_id 3 for calling the CooccurrenceVectorizerTest obj's underlying member method code with example usage: obj.test_enrich_utterance() without return types