public function addFeedableItems($items)
    {
        if (!is_array($items) && !($items instanceof \Traversable)) {
            throw new \InvalidArgumentException('You should pass an array or a collection of Feedable items');
        }

        foreach ($items as $feedable) {
            if (!$feedable instanceof Feedable) {
                throw new \InvalidArgumentException('Feedable items should implement Feedable interface');
            }

            $this->addItem($feedable->getFeedItem());
        }

        return $this;
    }