public class TTTException extends Exception {
  
  // Constructors are not inherited from the superclass (Exception),
  // so we must define them here explicitly. 
  
  // However, we can use "super" as a shortcut to call the constructors
  // of the superclass. 
  
  public TTTException() {
    super("This is an error in the Tic-Tac-Toe game!");
  }
  
  public TTTException(String msg) {
    super(msg);
  }
  
}