code: public <N> CompletableFutureQueue<T, N> thenCombineAsync(Function<R, N> nextTransformation) {
      final Function<T, CompletableFuture<N>> f = this.resultFunction
          .andThen(before -> before.thenComposeAsync(v -> supplyAsync(() -> nextTransformation.apply(v))));
      return new CompletableFutureQueue<>(f);
    }
docs: <p>thenCombineAsync.</p>
  
  @param nextTransformation a {@link java.util.function.Function} object.
  @param <N>                a N object.
  @return a {@link org.rapidpm.frp.reactive.CompletableFutureQueue} object.