public function renderSourceFragment($lines, $errline)
    {
        $output = "Source\n======\n";
        foreach ($lines as $offset => $line) {
            $output .= ($offset == $errline) ? "* " : "  ";
            $output .= str_pad("$offset:", 5);
            $output .= wordwrap($line, self::config()->columns, "\n       ");
        }
        $output .= "\n";

        return $output;
    }