public function add($item, $url = '')
    {
        $this->validateItemClassType($item);
        $this->createSitemapFile();

        $xmlData = $item->build();
        if (false === $this->isNewFileIsRequired() && false === $this->isSurpassingFileSizeLimit($xmlData)) {
            $this->appendToFile($xmlData);
            ++$this->totalItems;

            return $this;
        }

        $this->createAdditionalSitemapFile($item);

        return $this;
    }