docs: private IntTaggedWord getCachedITW(short tag) {
      // The +2 below is because -1 and -2 are used with special meanings (see IntTaggedWord).
      if (tagITWList == null) {
        tagITWList = new ArrayList<IntTaggedWord>(numTagBins + 2);
        for (int i=0; i<numTagBins + 2; i++) {
          tagITWList.add(i, null);
        }
      }
      IntTaggedWord headT = tagITWList.get(tagBin(tag) + 2);
      if (headT == null) {
        headT = new IntTaggedWord(ANY_WORD_INT, tagBin(tag));
        tagITWList.set(tagBin(tag) + 2, headT);
      }
      return headT;
    }