code: public PeriodicEvent runAfter(Runnable task, float delay) {
          validateDelay(delay);
          return new Event(task, delay);
      }
docs: Run a task once, after a delay.
  
  @param task
  Task to run.
  @param delay
  Unit is seconds.
  @return An interface that lets you query the status; cancel; or
  reschedule the event.