public ContextStack<T> copyPop() {
        final ContextStack<T> stack1 = copy();
        stack1.pop();
        return stack1;
    }
public ContextStack < T > copyPop ( ) { final ContextStack < T > stack1 = copy ( ) ; stack1 . pop ( ) ; return stack1 ; }
Return a new stack with the same contents but pop a value