if (tail.NE(Dequeue.TAIL_INITIAL_VALUE)) {
if (tail.NE(Deque.TAIL_INITIAL_VALUE)) {
  public void flushLocal() {    if (tail.NE(Dequeue.TAIL_INITIAL_VALUE)) {      closeAndEnqueueTail(queue.getArity());      tail = Dequeue.TAIL_INITIAL_VALUE;    }  }