long index = 0;

                @Override
                public boolean tryAdvance(Consumer<? super R> action) {
                  if (fromIterator.hasNext()) {
                    action.accept(function.apply(fromIterator.next(), index++));
                    return true;
                  }
                  return false;
                }
              },
              isParallel)

        return new Iterator<B>() {
          private final Iterator<? extends A> fromIterator = fromIterable.iterator();

          @Override
          public boolean hasNext() {
            return fromIterator.hasNext();
          }

          @Override
          public B next() {
            return convert(fromIterator.next());
          }

          @Override
          public void remove() {

        return new Iterator<B>() {
          private final Iterator<? extends A> fromIterator = fromIterable.iterator();

          @Override
          public boolean hasNext() {
            return fromIterator.hasNext();
          }

          @Override
          public B next() {
            return convert(fromIterator.next());
          }

          @Override
          public void remove() {