docs: def filter_repo_urls(candidates):
      """
      Filters down a list of URL candidates
      :param candidates: list, URL candidates
      :return: set, Repo URLs
      """
      # first, we are going to filter down the URL candidates to be all valid urls
      candidates = set(url for url in [validate_url(_url) for _url in candidates] if url)
      logger.info("Got repo candidates {}".format(candidates))
      repos = set(url for url in [validate_repo_url(_url) for _url in candidates] if url)
      logger.info("Filtered initial candidates down to {}".format(repos))
  
      return repos