static class LFunctionPlusPrevious extends LearnerImpl {
  static boolean debug;
  Stepper stepper;
  new List<O[]> examples;
  
  public void processInOut(O in, O out) {
    examples.add(new O[] {in, out});
    
    if (stepper == null)
      stepper = new Stepper(allFunctions(), solvedCases());

    while (!stepper.ended()) {
      if (check(stepper.current()))
        ret; // ok, keep
      else
        stepper.step();
    }
    
    fail();
  }

  boolean check(O[] fg) {
    if (debug) debug("Checking " + structure(fg));
    for (O[] e : examples) {
      O o = tryProcess((Function) fg[0], e[0]);
      if (o != null) {
        O x = tryProcess(((Case) fg[1]).winner, o);
        if (e[1].equals(x))
          continue; // example ok
      }
      ret false;
    }
    ret true; // all examples ok
  }
  
  public O processIn(O in) {
    Object[] fg = stepper.current();
    ret ((Case) fg[1]).processIn(((Function) fg[0]).process(in));
  }
  
  static class Stepper {
    List<Function> functions;
    List<Case> cases;
    int i1, i2;
    
    *(List<Function> *functions, List<Case> *cases) {}
    
    boolean ended() {
      ret i1 >= functions.size();
    }
    
    O[] current() {
      ret new O[] {functions.get(i1), cases.get(i2)};
    }
    
    void step() {
      if (i2 < cases.size()-1) ++i2;
      else { ++i1; i2 = 0; }
    }
  }
}