code: def write_sources_list(url, codename, filename='ceph.list', mode=0o644):
      
      repo_path = os.path.join('/etc/apt/sources.list.d', filename)
      content = 'deb {url} {codename} main\n'.format(
          url=url,
          codename=codename,
      )
      write_file(repo_path, content.encode('utf-8'), mode)
docs: add deb repo to /etc/apt/sources.list.d/