code: def testProbeCancel(self):
      comm = self.COMM.Dup()
      try:
          request = comm.Issend([None, 0, MPI.BYTE], comm.rank, 123)
          status = MPI.Status()
          comm.Probe(MPI.ANY_SOURCE, MPI.ANY_TAG, status)
          self.assertEqual(status.source, comm.rank)
          self.assertEqual(status.tag, 123)
          request.Cancel()
          self.assertTrue(request)
          status = MPI.Status()
          request.Get_status(status)
          cancelled = status.Is_cancelled()
          if not cancelled:
              comm.Recv([None, 0, MPI.BYTE], comm.rank, 123)
              request.Wait()
          else:
              request.Free()
      finally:
          comm.Free()
  
imports: from mpi4py import MPI
  import mpiunittest
  import itertools
  import arrayimpl
label_desc: Use image node_id 12 for calling the BaseTestP2PBuf obj's underlying member method code with example usage: obj.testProbeCancel() without return types