/**
     * Generate a URL friendly "slug" from a given string.
     *
     * @see https://github.com/illuminate/support/blob/master/Str.php
     *
     * @param  string  $title
     * @param  string  $separator
     * @param  string|null  $language
     *
     * @return string
     */
    public function slug(string $title, string $separator = '-', ?string $language = 'en')
    {
        $title = $language ? $this->ascii($title, $language) : $title;

        // Convert all dashes/underscores into separator
        $flip = $separator === '-' ? '_' : '-';

        $title = preg_replace('![' . preg_quote($flip) . ']+!u', $separator, $title);

        // Replace @ with the word 'at'
        $title = str_replace('@', $separator . 'at' . $separator, $title);

        // Remove all characters that are not the separator, letters, numbers, or whitespace.
        $title = preg_replace('![^' . preg_quote($separator) . '\pL\pN\s]+!u', '', $this->lower($title));

        // Replace all separator characters and whitespace by a single separator
        $title = preg_replace('![' . preg_quote($separator) . '\s]+!u', $separator, $title);

        return trim($title, $separator);
    }