srecord noeq StupidFib_collab(ICollab collab, int n) {
  double timeout = 10.0;
  
  // if n <= parallelizationThreshold, we calculate serially
  gettable int parallelizationThreshold = 8;
  settable int delay = 0; // millisecond delay per add
  
  selfType parallelizationThreshold(int x) {
    parallelizationThreshold = max(3, x); this;
  }
  
  record noeq Step(int n, LongConsumer continuation) extends LongPairCollector is Runnable {
    void complete(long a, long b) {
      continuation.accept(add(a, b));
    }
    
    run {
      // fallback to serial case
      if (n < parallelizationThreshold)
        ret with continuation.accept(serialComputation(n));

      collab.addWork(new Step(n-1, setterForA()));
      collab.addWork(new Step(n-2, setterForB()));
    }
  }
  
  long serialComputation(int n) {
    ret stupidFib(n);
  }
  
  long get() {
    // serial or parallel?
    if (collab.coresToUse() == 1)
      ret serialComputation(n);
    else
      ret collab_computeLong(receiver -> new Step(n, receiver));
  }
  
  long add(long a, long b) {
    if (delay > 0) sleep(delay);
    ret a+b;
  }  
}