code: public final <V> Mono<V> transform(Function<? super Mono<T>, ? extends Publisher<V>> transformer) {
  		return onAssembly(from(transformer.apply(this)));
  	}
docs: Transform this {@link Mono} in order to generate a target {@link Mono}. Unlike {@link #compose(Function)}, the
  provided function is executed as part of assembly.
  
  <pre>
  Function<Mono, Mono> applySchedulers = mono -> mono.subscribeOn(Schedulers.io())
  .publishOn(Schedulers.parallel());
  mono.transform(applySchedulers).map(v -> v * v).subscribe();
  </pre>
  <p>
  <img class="marble" src="doc-files/marbles/transformForMono.svg" alt="">
  
  @param transformer the {@link Function} to immediately map this {@link Mono} into a target {@link Mono}
  instance.
  @param <V> the item type in the returned {@link Mono}
  
  @return a new {@link Mono}
  @see #compose(Function) compose(Function) for deferred composition of {@link Mono} for each {@link Subscriber}
  @see #as(Function) as(Function) for a loose conversion to an arbitrary type