code: public ReactiveTask requestAsync(final long n) {
          return withSubscriptionAndTask(subscriptionAndTask.map2(c -> CompletableFuture.runAsync(() -> subscriptionAndTask._1().join()
                                                                                                                              .request(n),
                                                                                                  exec)));
      }
docs: Asyncrhonously request more elements from the Stream
  
  @param n Number of elements to request
  @return New ReactiveTask that references the execution of the new async task