code: def pathjoin(*parts, **kvs):
      '''join path parts into a path; in case url is not none, use that, too'''
      url = kvs.pop('url', '/')
      url = url + '/' + '/'.join(parts)
      url = normalize_url(url)
      return urf pathjoin(*parts, **kvs):
      '''join path parts into a path; in case url is not none, use that, too'''
      url = kvs.pop('url', '/')
      url = url + '/' + '/'.join(parts)
      url = normalize_url(url)
      return url
docs: join path parts into a path; in case url is not none, use that, too