<metal:cacheheaders define-macro="cacheheaders"
    tal:define="portal_state context/@@plone_portal_state;
                lang context/Language|nothing;
                lang python: lang or portal_state.default_language();
                setHeader python:request.RESPONSE.setHeader;">
    <metal:block tal:define="dummy python:setHeader('Content-Type', 'text/html;;charset=utf-8')" />
    <metal:block tal:define="dummy python:setHeader('Content-Language', lang)" />
    <metal:block tal:define="dummy python:setHeader('Expires', 'Sat, 1 Jan 2000 00:00:00 GMT')" />
    <tal:gzip tal:replace="nothing">
      Use the following line to enable gzip compression
      tal:content="structure python:context.enableHTTPCompression(request=request, enable=1)"
    </tal:gzip>
</metal:cacheheaders>
