static Q mechAppendQueue_q;
static Lock mechAppendQueue_lock = lock();

static Q mechAppendQueue() {
  lock mechAppendQueue_lock;
  if (mechAppendQueue_q == null)
    mechAppendQueue_q = startQ();
  ret mechAppendQueue_q;
}

static void mechAppendQueue(Runnable r) {
  mechAppendQueue().add(r);
}