code: @Override
    public int mustFindValueFor(final int slotNo) {
      final int index = find(auxIntArr, lgAuxArrInts, lgConfigK, slotNo);
      if (index >= 0) {
        return HllUtil.getValue(auxIntArr[index]);
      }
      throw new SketchesStateException("SlotNo not found: " + slotNo);
    }
docs: In C: two-registers.c Line 205