sS ai_ruleOfThree_solver_1(S db, S input) {
  new TransformersOnObjects too;
  too.addAll(lambdaMap ai_parseBasicLogicRule(tlft(db)));
  too.add(Input(input));

  // for word appearing in LHS and RHS: turn word into variable
  too.addTransformer(func(BasicLogicRule<S> r) -> BasicLogicRule {
    ai_sharedWordsIntoDollarVars(r)
  });

  // match input with rules
  too.addTransformer(func(BasicLogicRule<S> r) {
    if (containsDollarVars(r.lhs))
      too.addTransformer(func(Input i) {
        S s = cast i.a;
        for (SS map : flexMatchDollarVarsIC_all(r.lhs, s))
          too.add(TransformedInput(replaceVars(r.rhs, map)));
        null;
      });
    null;
  });

  ret withDeepReturn(returnSite -> {
    // return first transformed input
    too.addTransformer(func(TransformedInput i) {
      deepReturn(returnSite, (S) i.a);
      null;
    });
    too.think();
  });
}