code: def test_None(self):
      # test None
      result = utils.is_corpus(None)
      expected = (False, None)
      self.assertEqual(expected, result)
  
imports: import logging
  import unittest
  import numpy
  from gensim import utils
  from gensim.test.utils import datapath, get_tmpfile
label_desc: Use image node_id 1 for calling the TestIsCorpus obj's underlying member method code with example usage: obj.test_None() without return types