abstract sclass LogicAgent {
  Collection<AIConcept> concepts;  // input
  new LinkedHashSet<S> statements; // output

  abstract void impl();
  
  void emit(S s) {
    if (statements.add(s))
      print("> " + s);
  }
  
  void runLive(bool doIt) {
    concepts = aiConcepts();
    statements.clear();
    impl();
    if (doIt)
      addTruth(statements);
  }
}