static Collection<GInterpretable> gazelle_preprocess(S input1, O... _) {
  new L<GInterpretable> interpretables;
  int max = optPar max(_, 20);
  Collector<GInterpretable> collector = limitedCollector(interpretables, max);
  
  new Map<S> evalCache;
  F1<S> eval = boolPar noEvals(_) ? f_id()
    : func(S s) -> S { gazelle_processSafeEvals(s, evalCache) };

  input1 = callF(eval, input1);
  Set<S> texts = litCISet(input1);
  collector.add(GInterpretable(input1));
  RuleEngine2 engine = ((F0<GazelleEvalContext>) optPar contextMaker(_)).get().engine;
  

  int nInterpreted = 0;
  
  bigLoop: while (!collector.full() && nInterpreted < l(interpretables)) {
    GInterpretable workingOn = get(interpretables, nInterpreted);
    S input = workingOn.text;
    S ruleBase = empty(workingOn.ruleID) ? "" : workingOn.ruleID + "+";
    ++nInterpreted;
    
    for (RuleEngine2.SimplifyWithRule rule : engine.splitterRules()) pcall {
      for (S out : gazelle_executeSplitterRule(engine, rule, input))
        if (texts.add(out = callF(eval, out)))
          if (collector.add(new GInterpretable(out, ruleBase + rule.globalID))) break bigLoop;
    }
    
    for (GazelleTree t : dm_gazelle_reasonAboutChatInput_v2(null, input, 
      paramsPlus(_, skipSplitters := true, acceptablePurposes := litset('preprocess), skipUserName := true, skipUserID := true))) {
        S s = callF(eval, t.line);
        if (texts.add(s))
          if (collector.add(new GInterpretable(
            s, ruleBase + t.ruleID(), t.mr)))
              break bigLoop;
    }
  }
      
  ret interpretables;
}