// A == Bool
sclass SelectBot<A> extends Concept {
  new TreeMap<S, A> examples;
  new TreeMap<S, A> guessed;
  transient S lastMatch; // not used
  
  void put(S s, A value) {
    examples.put(s, value);
    guessed.remove(s);
    change();
  }

  A get(S s) {
    A value = (A) guess_match(s);
    if (neq(examples.get(s), value))
      if (mapPutIfChange(guessed, s, value)) change();
    ret value;
  }
}