docs: public static ArrayList<TaggedWord> toTaggedList(List<String> lex, List<String> tags) {
      ArrayList<TaggedWord> sent = new ArrayList<TaggedWord>();
      int ls = lex.size();
      int ts = tags.size();
      if (ls != ts) {
        throw new IllegalArgumentException("Sentence.toSentence: lengths differ");
      }
      for (int i = 0; i < ls; i++) {
        sent.add(new TaggedWord(lex.get(i), tags.get(i)));
      }
      return sent;
    }