(self, response)
return '110 - "Response is Stale"'
Return a valid 1xx warning header value describing the cache
        adjustments.

        The response is provided too allow warnings like 113
        http://tools.ietf.org/html/rfc7234#section-5.5.4 where we need
        to explicitly say response is over 24 hours old.
Return a valid 1xx warning header value describing the cache
        adjustments.
Return a valid 1xx warning header value describing the cache adjustments .
def warning(self, response):
        """
        Return a valid 1xx warning header value describing the cache
        adjustments.

        The response is provided too allow warnings like 113
        http://tools.ietf.org/html/rfc7234#section-5.5.4 where we need
        to explicitly say response is over 24 hours old.
        """
        return '110 - "Response is Stale"'
def warning ( self , response ) : return '110 - "Response is Stale"'