static L<GazelleTree> gazelle_reasonWithPreprocessing(S input1, O... _) {

  F0<GazelleEvalContext> contextMaker = cast assertNotNull("Need contextMaker", optPar contextMaker(_));

  S userName = stringPar userName(_);

  bool debug = boolPar debug(_);

  bool debugPreprocessing = boolPar debugPreprocessing(_);

  Collector<GInterpretable> interpretables_out = cast optPar interpretables_out(_);

  Collection<GInterpretable> interpretables = gazelle_preprocess(input1, _);

  if (debugPreprocessing) {

    print("Got " + n2(interpretables, "interpretable") + ".");

    printIndentLines(interpretables);

  }

  if (interpretables != null) addAll(interpretables_out, interpretables); 

  Set<S> acceptablePurposes = cast optPar acceptablePurposes(_);

  if (acceptablePurposes == null) acceptablePurposes = litset("");

  new L<GazelleTree> l2;

  Set<S> outputs = ciSet();

  for (GInterpretable intp : interpretables) {

    L<GazelleTree> results = dm_gazelle_reasonAboutChatInput_v2(userName, intp.text, paramsPlus(_, +acceptablePurposes));

    print(intp.text + " => " + n2(results, "result"));

    for (GazelleTree tree : results)

      if (outputs.add(tree.line)) {

        if (tree.mr != null) tree.mr.interpretable = intp;

        l2.add(tree);

      }

  }

  gazelle_dropMatchedDefaultRules(l2, _);

  ret l2;

}