public class PairTest{
  
  public static void main(String[] args){
    Pair<String> p1 = new Pair<String>("hello", "world");
    System.out.println("Before swap():");
    System.out.println(p1);
    p1.swap();
    System.out.println("After swap():");
    System.out.println(p1);
    
    System.out.println();
    
    Pair<Widget> p2 = new Pair<Widget>(new Widget(50), new Widget(100));
    System.out.println("Before swap():");
    System.out.println(p2);
    p2.swap();
    System.out.println("After swap():");
    System.out.println(p2);
  } 
}