code: def test_basic(self):
      # test for matrix case
      mdiff, annotation = self.model.diff(
          self.model, n_ann_terms=self.n_ann_terms
      )
  
      self.assertEqual(mdiff.shape, (self.num_topics, self.num_topics))
      self.assertEqual(len(annotation), self.num_topics)
      self.assertEqual(len(annotation[0]), self.num_topics)
  
      # test for diagonal case
      mdiff, annotation = self.model.diff(
          self.model, n_ann_terms=self.n_ann_terms, diagonal=True
      )
  
      self.assertEqual(mdiff.shape, (self.num_topics,))
      self.assertEqual(len(annotation), self.num_topics)
  
file_path: gensim/gensim/test/test_tmdiff.py
imports: import logging
  import unittest
  import numpy
  from gensim.models import LdaModel
  from gensim.test.utils import common_dictionary, common_corpus
label_desc: Use image node_id 2 for calling the TestLdaDiff obj's underlying member method code with example usage: obj.test_basic() without return types