sclass SingleThread {
  bool running;
  Thread thread;
  
  void run(O r) { go(r); }
  
  synchronized bool go(final O runnable) {
    if (running) false;
    running = true;
    thread = startThread("Single Thread", r {
      try {
        callF(runnable);
      } finally {
        _done();
      }
    });
    true;
  }
  
  synchronized void _done() {
    running = false;
    thread = null;
  }
  
  synchronized bool running() { ret running; }
  
  synchronized Thread getThread() { ret thread; }
}