docs: def url_to_path(url):
      """
      Convert a file: URL to a path.
      """
      assert url.startswith('file:'), (
          "You can only turn file: urls into filenames (not %r)" % url)
      path = url[len('file:'):].lstrip('/')
      path = urllib.unquote(path)
      if _url_drive_re.match(path):
          path = path[0] + ':' + path[2:]
      else:
          path = '/' + path
      return path