MatthiasMullie\Scrapbook\Psr6\Pool::save PHP Method

    public function save(CacheItemInterface $item)
    {
        if (!$item instanceof Item) {
            throw new InvalidArgumentException('MatthiasMullie\\Scrapbook\\Psr6\\Pool can only save
                MatthiasMullie\\Scrapbook\\Psr6\\Item objects');
        }
        if (!$item->hasChanged()) {
            /*
             * If the item didn't change, we don't have to re-save it. We do,
             * however, need to check if the item actually holds a value: if it
             * does, it should be considered "saved" (even though nothing has
             * changed, the value for this key is in cache) and if it doesn't,
             * well then nothing is in cache.
             */
            return $item->get() !== null;
        }
        $expire = $item->getExpiration();
        return $this->store->set($item->getKey(), $item->get(), $expire);
    }