Relax\Greppy\FluentPattern::literal PHP Method

    public function literal()
    {
        $characters = func_get_args();
        $pattern = count($characters) > 1 ? "[%s]" : "%s";
        $escapedCharacters = array();
        foreach ($characters as $c) {
            $escapedCharacters[] = ctype_alnum($c) ? $c : sprintf("\\%s", $c);
        }
        $this->pattern .= sprintf($pattern, implode("", $escapedCharacters));
        return $this;
    }