code: def make_series_url(key):
      
  
      url = urlparse.urljoin(endpoint.SERIES_ENDPOINT, 'key/')
      url = urlparse.urljoin(url, urllib.quote(key))
      return url
docs: For internal use. Given a series key, generate a valid URL to the series
      endpoint for that key.
  
      :param string key: the series key
      :rtype: string