code: public static <T> Promise<Void> acceptAll(ChannelConsumer<T> output, Iterator<? extends T> it) {
  		if (!it.hasNext()) return Promise.complete();
  		return Promise.ofCallback(cb -> acceptAllImpl(output, it, cb));
  	}
docs: Passes iterator's values to the {@code output} until it {@code hasNext()},
  then returns a promise of {@code null} as a marker of completion.
  <p>
  If there was an exception while accepting iterator, a promise of
  exception will be returned.
  
  @param output a {@code ChannelConsumer}, which accepts the iterator
  @param it     an {@link Iterator} which provides some values
  @param <T>    a data type of passed values
  @return a promise of {@code null} as a marker of completion