code: public static Mono<Long> delay(Duration duration, Scheduler timer) {
  		return onAssembly(new MonoDelay(duration.toMillis(), TimeUnit.MILLISECONDS, timer));
  	}
docs: Create a Mono which delays an onNext signal by a given {@link Duration duration}
  on a provided {@link Scheduler} and completes.
  If the demand cannot be produced in time, an onError will be signalled instead.
  
  <p>
  <img class="marble" src="doc-files/marbles/delay.svg" alt="">
  <p>
  @param duration the {@link Duration} of the delay
  @param timer a time-capable {@link Scheduler} instance to run on
  
  @return a new {@link Mono}