code: def _get_cookie_referrer_host(self):
          '''Return the referrer hostname.'''
          referer = self._original_request.fields.get('Referer')
  
          if referer:
              return URLInfo.parse(referer).hostname
          else:
              return Nonf _get_cookie_referrer_host(self):
          '''Return the referrer hostname.'''
          referer = self._original_request.fields.get('Referer')
  
          if referer:
              return URLInfo.parse(referer).hostname
          else:
              return None
docs: Return the referrer hostname.