public class LockedSt implements State {
  private static LockedSt instance = new LockedSt();
  public static State createInstance() {
    return instance;
  }
  private LockedSt() {}
  public State coin(Mediator m) {
    m.unlock();
    return UnlockedSt.createInstance();
  }
  public State pass(Mediator m) {
    m.alarm();
    return FinedSt.createInstance();
  }
}