public class WalkablesTest 
{
    public static void main(String[] args) 
    {
        Walkable[] w = new Walkable[5];
        w[0] = new Person("Jack");
        w[1] = new Person("Manfred");
        w[2] = new Duck("Donald");
        w[3] = new Fish("John");
        w[4] = new Duck("Dagobert");
        
        // Let them walk
        Walkables.letThemWalk(w);
   
    }
}