private function parseExport($raw_line)
    {
        $line = trim($raw_line);

        if ($this->string_helper->startsWith("export", $line)) {
            $export_line = explode("export", $raw_line, 2);

            if (count($export_line) !== 2 || empty($export_line[1])) {
                throw new ParseException(
                    'You must have a export key = value',
                    $raw_line,
                    $this->line_num
                );
            }

            $line = trim($export_line[1]);
        }

        return $line;
    }