public function getExportFilename(array $fieldgroup) : array
    {
        if ($key = array_search($fieldgroup['key'], $this->exportPosts)) {
            return array(
                'php' => $key . '.php',
                'json' => $key . '.json'
            );
        }

        return array(
            'php' => sanitize_title($fieldgroup['title']) . '.php',
            'json' => sanitize_title($fieldgroup['title']) . '.json'
        );
    }