switch (totalCharacters) {
      case 0:
        return none();
      case 1:
        return is((char) table.nextSetBit(0));
      case 2:
        char c1 = (char) table.nextSetBit(0);
        char c2 = (char) table.nextSetBit(c1 + 1);
        return isEither(c1, c2);
      default:
        return isSmall(totalCharacters, table.length())

          @CheckForNull
          protected Set<E> computeNext() {
            if (bits.isEmpty()) {
              bits.set(0, size);
            } else {
              int firstSetBit = bits.nextSetBit(0);
              int bitToFlip = bits.nextClearBit(firstSetBit);

              if (bitToFlip == index.size()) {
                return endOfData();
              }

              /*