docs: def path_dirs(urls):
      '''
      Takes a StringCounter of normalized URL and parses them into
      a list of path directories. The file name is
      included in the path directory list.
      '''
      path_dirs = StringCounter()
      for url in urls:
          for path_dir in filter(None, urlparse(url).path.split('/')):
              path_dirs[path_dir] += urls[url]
      return path_dirs