};
        final Supplier<InputLocation> locationSupplier = () -> {
            if (stk.size() < 2) {
                return null;
            }
            Iterator<ActivationFrame> f = stk.iterator();

            String location = f.next().location;
            ActivationFrame parent = f.next();

            return parent.parent.map(p -> p.getLocation(location)).orElse(null);
        };