import objectdraw.*;

/*
 * An empty stack of balls.  This implements the stack
 * interface, but only the isEmpty method should be used.
 */
public class EmptyStack implements StackInterface {

        public EmptyStack() {
        }

        public boolean isEmpty() {
                return true;
        }
        
        // return null as a default value
        public VisibleImage getFirst() {
                return null;
        }
        
        // return null as a default value
        public StackInterface getRest() {
                return null;
        }
        
}