code: def _repos_checked(self, worker, output, error):
          
          if worker.repo in self._checking_repos:
              self._checking_repos.remove(worker.repo)
  
          if output:
              self._valid_repos.append(worker.repo)
  
          if len(self._checking_repos) == 0:
              self._download_repodata(self._valid_repos)
docs: Callback for _check_repos.