code: public static <E> SingleConsumerQueue<E> optimistic() {
      @SuppressWarnings("unchecked")
      Function<E, Node<E>> factory = (Function<E, Node<E>>) OPTIMISIC;
      return new SingleConsumerQueue<>(factory);
    }
docs: Creates a queue with an optimistic backoff strategy. A thread completes its operation
  without waiting after it successfully hands off the additional element(s) to another producing
  thread for batch insertion. This optimistic behavior may result in additions not appearing in
  FIFO order due to the backoff strategy trying to compensate for queue contention.
  
  @param <E> the type of elements held in this collection
  @return a new queue where producers complete their operation immediately if combined with
  another producing thread's