final ImmutableList<E> elements = inputSet.keySet().asList();
        int remainingSetBits = mask;

        @Override
        public boolean hasNext() {
          return remainingSetBits != 0;
        }

        @Override
        public E next() {
          int index = Integer.numberOfTrailingZeros(remainingSetBits);
          if (index == 32) {
            throw new NoSuchElementException();