code: def _check_repos(self, repos):
          
          self._checking_repos = []
          self._valid_repos = []
  
          for repo in repos:
              worker = self.download_is_valid_url(repo)
              worker.sig_finished.connect(self._repos_checked)
              worker.repo = repo
              self._checking_repos.append(repo)
docs: Check if repodata urls are valid.