gistfile1.java

class List {
	public Item removeFirst() throws ListException {
		if (this.count() <= 0) throw new ListException("no more item");

		Item item = /* remove the first item from the list */;
		return item;
	}
}

class Stack {
	private List list;

	public item pop1() throws StackException{
		if (list.count() <= 0) throw new StackException("no more item");

		try {
			return list.removeFirst();
		} catch (ListException exception) { }

		return null; // rarely reachable
	}

	public item pop2() throws ListException {
		return list.removeFirst();
	}
}