public function getByFileName($fileName)
    {
        if (!isset($this->templates[$fileName])) {
            /** @var \Tx_Oelib_Template $template */
            $template = GeneralUtility::makeInstance(\Tx_Oelib_Template::class);

            if ($fileName !== '') {
                $template->processTemplateFromFile($fileName);
            }
            $this->templates[$fileName] = $template;
        }

        return clone $this->templates[$fileName];
    }