code: def to_http_string(self):
          
          return self.language_code[:2] if self.country_code is None \
                  else '%s-%s' % (self.language_code[:2], self.country_code)
docs: Return the string representation of the locale compatible with the
          HTTP header ``Accept-Language`` as specified in `RFC 7231
          <https://tools.ietf.org/html/rfc7231#section-5.3.5>_`
  
          The Accept-Language request HTTP header advertises which languages the
          client is able to understand, and which locale variant is preferred.
  
  
          @return: a string representation of this locale compatible with HTTP
              request, i.e., a ISO 639-3 alpha-2, optionally followed by a dash
              character ``-`` and a ISO 3166-1 alpha-2 code.