code: protected function execute(InputInterface $input, OutputInterface $output)
      {
          $baseUrl = $input->getArgument('url');
          $crawlProfile = $input->getOption('dont-crawl-external-links') ? new CrawlInternalUrls($baseUrl) : new CrawlAllUrls();
  
          $output->writeln("Start scanning {$baseUrl}");
          $output->writeln('');
  
          $crawlLogger = new CrawlLogger($output);
  
          if ($input->getOption('output')) {
              $outputFile = $input->getOption('output');
  
              if (file_exists($outputFile)) {
                  $helper = $this->getHelper('question');
                  $question = new ConfirmationQuestion(
                      "The output file `{$outputFile}` already exists. Overwrite it? (y/n)",
                      false
                  );
  
                  if (! $helper->ask($input, $output, $question)) {
                      $output->writeln('Aborting...');
  
                      return 0;
                  }
              }
  
              $crawlLogger->setOutputFile($input->getOption('output'));
          }
  
          $clientOptions = [
              RequestOptions::TIMEOUT => $input->getOption('timeout'),
              RequestOptions::VERIFY => ! $input->getOption('skip-verification'),
              RequestOptions::ALLOW_REDIRECTS => false,
          ];
  
          $clientOptions = array_merge($clientOptions, $input->getOption('options'));
  
          if ($input->getOption('user-agent')) {
              $clientOptions[RequestOptions::HEADERS]['user-agent'] = $input->getOption('user-agent');
          }
  
          $crawler = Crawler::create($clientOptions)
              ->setConcurrency($input->getOption('concurrency'))
              ->setCrawlObserver($crawlLogger)
              ->setCrawlProfile($crawlProfile);
  
          if ($input->getOption('ignore-robots')) {
              $crawler->ignoreRobots();
          }
  
          $crawler->startCrawling($baseUrl);
  
          return 0;
      }
docs: @param \Symfony\Component\Console\Input\InputInterface $input
  @param \Symfony\Component\Console\Output\OutputInterface $output
  
  @return int