docs: private void cleanPipes()
      {
          assert (pipe != null);
  
          //  Get rid of half-processed messages in the out pipe. Flush any
          //  unflushed messages upstream.
          pipe.rollback();
          pipe.flush();
          //  Remove any half-read message from the in pipe.
          while (incompleteIn) {
              Msg msg = pullMsg();
              if (msg == null) {
                  assert (!incompleteIn);
                  break;
              }
              // msg.close ();
          }
      }