docs: def fetch_lid(self, woeid):
          """Fetch a location's corresponding LID.
  
          Args:
              woeid: (string) the location's WOEID.
  
          Returns:
              a string containing the requested LID or None if the LID could
              not be found.
  
          Raises:
              urllib.error.URLError: urllib.request could not open the URL
                  (Python 3).
              urllib2.URLError: urllib2 could not open the URL (Python 2).
              xml.etree.ElementTree.ParseError: xml.etree.ElementTree failed to
                  parse the XML document.
  
          """
          rss = self._fetch_xml(LID_LOOKUP_URL.format(woeid, "f"))
  
          # We are pulling the LID from the permalink tag in the XML file
          # returned by Yahoo.
  
          try:
              link = rss.find("channel/link").text
          except AttributeError:
              return None
  
          # use regex or string.split
          # regex assumes the format XXXXNNNN for the LID.
          # string.split works more general of the context.
  
          lid = re.search("[A-Za-z]{4}[0-9]{4}", link).group()
          # lid = link.split("/forecast/")[1].split("_")[0]
  
          return lid