public class singleton extends letter {  
   singleton  
  
  static int number = 0;
  
  protected singleton() { }
  
  
  static letter instance() {
  	if (number==0) {
  		theletter = new letter();
  		number = 1;
  		}
  	return theletter;
  	}
  
  public void message() {
  	System.out.println("Message in a letter");
  	}
  
  static letter theletter;
  };