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

    public function saveDeferred(CacheItemInterface $item)
    {
        if (!$item instanceof Item) {
            throw new InvalidArgumentException('MatthiasMullie\\Scrapbook\\Psr6\\Pool can only save
                MatthiasMullie\\Scrapbook\\Psr6\\Item objects');
        }
        $this->deferred[$item->getKey()] = $item;
        // let's pretend that this actually comes from cache (we'll store it
        // there soon), unless if it's already expired (in which case it will
        // never reach cache...)
        $item->overrideIsHit(!$item->isExpired());
        return true;
    }