static Set<S> gazelle_inputExamplesFromRules(O... _) {
  F0<GazelleEvalContext> contextMaker = gazelle_contextMakerFromParams(_);
  Set<S> examples = ciSet();
  L<RuleEngine2.Rule> rules = filter(contextMaker->engine.rules, r
    -> eqOneOf(r.purpose, 'preprocess, "")
    && !contains(r.comments, "disable"));
  for (RuleEngine2.Rule r : rules) {
    GRuleLine in = first(r.insWithType);
    if (in != null && eq(in.type, "standard"))
      examples.add(in.text);
  }
  ret examples;
}