code: def test_None(self):
      # test None
      result = matutils.isbow(None)
      expected = False
      self.assertEqual(expected, result)
  
imports: import logging
  import unittest
  from gensim import matutils
  from scipy.sparse import csr_matrix
  import numpy
  import math
  from gensim.corpora.mmcorpus import MmCorpus
  from gensim.models import ldamodel
  from gensim.test.utils import datapath, common_dictionary, common_corpus
label_desc: Use image node_id 1 for calling the TestIsBow obj's underlying member method code with example usage: obj.test_None() without return types