public function merge(ActivityFeed $newerFeed): ActivityFeed
    {
        if (count($this->getItems()) > 0) {
            $prepend = $newerFeed->getItemsAfter($this->getItems()[0]);
        } else {
            $prepend = $newerFeed->getItems();
        }

        return new ActivityFeed(array_merge($prepend, $this->getItems()));
    }