code: Stage<Void> doCollectAndDiscard(
        Collection<? extends Stage<?>> stages
    ) {
      final Completable<Void> target = completable();
  
      final CollectAndDiscardHelper done = new CollectAndDiscardHelper(stages.size(), target);
  
      for (final Stage<?> q : stages) {
        q.handle(done);
      }
  
      bindSignals(target, stages);
      return target;
    }
docs: Perform a collect and discard.
  
  @param stages stages to discard
  @return a completable