code: def testBuffering(self):
      comm = self.COMM.Dup()
      buf = MPI.Alloc_mem((1 << 16) + MPI.BSEND_OVERHEAD)
      try:
          with self.catchNotImplementedError(4, 1):
              comm.Attach_buffer(buf)
          with self.catchNotImplementedError(4, 1):
              comm.Flush_buffer()
          with self.catchNotImplementedError(4, 1):
              comm.Iflush_buffer().Wait()
      finally:
          with self.catchNotImplementedError(4, 1):
              oldbuf = comm.Detach_buffer()
              self.assertEqual(oldbuf.address, buf.address)
              self.assertEqual(oldbuf.nbytes, buf.nbytes)
          MPI.Free_mem(buf)
          with self.catchNotImplementedError(4, 1):
              comm.Attach_buffer(MPI.BUFFER_AUTOMATIC)
              bufauto = comm.Detach_buffer()
              self.assertEqual(bufauto, MPI.BUFFER_AUTOMATIC)
          comm.Free()
  
imports: from mpi4py import MPI
  import mpiunittest
label_desc: Use image node_id 22 for calling the BaseTestComm obj's underlying member method code with example usage: obj.testBuffering() without return types