sS ai_verifyDetector(IPred<S> detector, S posLines, S negLines) {
  LS posExamples = tlft(posLines);
  LS negExamples = tlft(negLines);
  LPair<S, Bool> examples = trueFalseBPairs(posExamples, negExamples);
  new LS good;
  new LS bad;
  new Scorer scorer;
  
  long time = sysNow();
  for (Pair<S, Bool> example : examples) {
    bool result = detector.get(example.a);
    bool ok = result == example.b;
    scorer.add(ok);
    S line = (ok ? "OK" : example.b ? "False negative" : "False positive") + ": " + example.a;
    (ok ? good : bad).add(line);
  }
  time = sysNow()-time;

  ret "Score for detector: " + scorer + "\n"
    + n2(good, "correct answer") + ", " + n2(bad, "bad answer") + ". Runtime: " + n2(time) + " ms\n\n"
    + or2(trim(lines(concatLists(bad, ll(""), good))), "No errors");
}