code: def testAccumulatorCachingWithTopnSettingGivenModel(self):
      kwargs = dict(
          corpus=self.corpus,
          dictionary=self.dictionary,
          topn=5,
          coherence="u_mass",
      )
      cm1 = CoherenceModel(model=self.ldamodel, **kwargs)
      cm1.estimate_probabilities()
      self.assertIsNotNone(cm1._accumulator)
  
      accumulator = cm1._accumulator
      topics_before = cm1._topics
      cm1.topn = 3
      self.assertEqual(accumulator, cm1._accumulator)
      self.assertEqual(3, len(cm1.topics[0]))
      self.assertEqual(topics_before, cm1._topics)
  
      cm1.topn = 6  # should be able to expand given the model
      self.assertEqual(6, len(cm1.topics[0]))
  
imports: import logging
  import unittest
  import multiprocessing
  from functools import partial
  import numpy
  from gensim.matutils import argsort
  from gensim.models.coherencemodel import CoherenceModel, BOOLEAN_DOCUMENT_BASED
  from gensim.models.ldamodel import LdaModel
  from gensim.test.utils import get_tmpfile, common_texts, common_dictionary, common_corpus
label_desc: Use image node_id 22 for calling the TestCoherenceModel obj's underlying member method code with example usage: obj.testAccumulatorCachingWithTopnSettingGivenModel() without return types