code: def test_index_accumulation(self):
      accumulator = CorpusAccumulator(self.top_ids).accumulate(
          self.corpus
      )
      inverted_index = accumulator.index_to_dict()
      expected = {
          10: {0, 2, 3},
          15: {0},
          20: {0},
          21: {1, 2, 3},
          17: {1, 2},
      }
      self.assertDictEqual(expected, inverted_index)
  
      self.assertEqual(3, accumulator.get_occurrences(10))
      self.assertEqual(2, accumulator.get_occurrences(17))
      self.assertEqual(2, accumulator.get_co_occurrences(10, 21))
      self.assertEqual(1, accumulator.get_co_occurrences(10, 17))
  
imports: import logging
  import unittest
  from gensim.corpora.dictionary import Dictionary
  from gensim.topic_coherence.text_analysis import InvertedIndexAccumulator, WordOccurrenceAccumulator, ParallelWordOccurrenceAccumulator, CorpusAccumulator
  from gensim.test.utils import common_texts
label_desc: Use image node_id 2 for calling the TestCorpusAnalyzer obj's underlying member method code with example usage: obj.test_index_accumulation() without return types