public function toSlugCase($replacement = '-', $language = 'en', $strToLower = true)
    {
        if (!class_exists('\\voku\\helper\\URLify'))
        {
            throw new \RuntimeException
            (
                "This method requires \voku\helper\URLify. ".
                "Install with: composer require voku/urlify"
            );
        }

        return $this->newSelf
        (
            \voku\helper\URLify::slug
            (
                $this->scalarString,
                $language,
                $replacement,
                $strToLower
            )
        );
    }