static Scorer dm_gazelle_checkPredictor(F2<RuleEngine2_MatchedRule, Collection<S>, S> predictor, O... _) {
  bool verbose = boolPar verbose(_);
  S ruleID = optPar ruleID(_);
  new Map<S, Set<S>> statementsByRule;
  new Scorer scorer;
  for (dm_gazelle_appliedRulesForLearning_Entry e : dm_gazelle_appliedRulesForLearning_withoutChangedRules()) {
    if (ruleID != null && neq(e.ruleID, ruleID)) continue;
    Set<S> set = getOrCreateTreeSet(statementsByRule, e.ruleID);
    if (nempty(set)) {
      if (verbose)
        print("Have " + n2(set, "statement"));
      ai_gazelle_analyzeStatementsForRule_Data data = ai_gazelle_analyzeStatementsForRule(set);
      S guess = "good";
      if (containsAny(keys(e.r.map), data.varsUsedInBadOnly))
        guess = "bad";
      scorer.add(eq(guess, e.judgement));
      if (verbose)
        print("  " + guess + "/" + e.judgement + ": " + e.r.map);
    }
  
    LS statements = ai_gazelle_statementsFromAppliedRule(e.r, e.judgement);
    set.addAll(statements);
  }
  ret scorer;
}