code: protected static ForkJoinTask<?> pollNextLocalTask() {
      Thread t;
      return ((t = Thread.currentThread()) instanceof ForkJoinWorkerThread)
          ? ((ForkJoinWorkerThread) t).workQueue.nextLocalTask()
          : null;
    }
docs: Unschedules and returns, without executing, the next task queued by the current thread but not
  yet executed, if the current thread is operating in a ForkJoinPool. This method is designed
  primarily to support extensions, and is unlikely to be useful otherwise.
  
  @return the next task, or {@code null} if none are available