static S guessGermanOrEnglish(S text) {
  Set<S> set1 = mechCISet("English words");
  Set<S> set2 = mechCISet("Deutsche Wörter");
  int score = 0;
  for (S word : words(text))
    score += zeroOne(set1.contains(word))-zeroOne(set2.contains(word));
  ret score > 0 ? "english" : score < 0 ? "german" : null;
}