public function propFind(PropFind $propFind, INode $node)
    {
        // There's a bunch of properties that must appear as a self-closing
        // xml-element. This event handler ensures that this will be the case.
        $props = [
            '{http://calendarserver.org/ns/}subscribed-strip-alarms',
            '{http://calendarserver.org/ns/}subscribed-strip-attachments',
            '{http://calendarserver.org/ns/}subscribed-strip-todos',
        ];

        foreach ($props as $prop) {
            if (200 === $propFind->getStatus($prop)) {
                $propFind->set($prop, '', 200);
            }
        }
    }