code: def testMessageNull(self):
      null = MPI.MESSAGE_NULL
      self.assertFalse(null)
      null2 = MPI.Message()
      self.assertEqual(null, null2)
      null3 = MPI.Message(null)
      self.assertEqual(null, null3)
  
imports: from mpi4py import MPI
  import mpiunittest
  import arrayimpl
label_desc: Use image node_id 1 for calling the TestMessage obj's underlying member method code with example usage: obj.testMessageNull() without return types