code: def testNull(self):
      GROUP_NULL = MPI.GROUP_NULL
      group_null = MPI.Group()
      self.assertFalse(GROUP_NULL)
      self.assertFalse(group_null)
      self.assertEqual(group_null, GROUP_NULL)
  
imports: from mpi4py import MPI
  import mpiunittest
label_desc: Use image node_id 2 for calling the TestGroupNull obj's underlying member method code with example usage: obj.testNull() without return types