code: @NonNull
      public Disposable scheduleDirect(@NonNull Runnable run) {
          return scheduleDirect(run, 0L, TimeUnit.NANOSECONDS);
      }
docs: Schedules the given task on this Scheduler without any time delay.
  
  <p>
  This method is safe to be called from multiple threads but there are no
  ordering or non-overlapping guarantees between tasks.
  
  @param run the task to execute
  
  @return the Disposable instance that let's one cancel this particular task.
  @since 2.0