code: public boolean cancel(boolean ign) {
      assert op != null : "No operation";
      op.cancel();
      notifyListeners();
      return op.getState() == OperationState.WRITE_QUEUED;
    }
docs: Cancel this operation, if possible.
  
  @param ign not used
  @deprecated
  @return true if the operation has not yet been written to the network