static S wordScoreBySet(S text, Set<S> set1, Set<S> set2, S a, S b) {
  int score = 0;
  for (S word : words(text))
    score += zeroOne(set1.contains(word))-zeroOne(set2.contains(word));
  ret score > 0 ? a : score < 0 ? b : null;
}