public function setFlagHeaders($eventObject) {
        $response = $eventObject->getResponse();
        if (Mage::helper('turpentine/esi')->shouldResponseUseEsi()) {
            $response->setHeader('X-Turpentine-Esi',
                Mage::registry('turpentine_esi_flag') ? '1' : '0');
            Mage::helper('turpentine/debug')->logDebug(
                'Set ESI flag header to: %s',
                (Mage::registry('turpentine_esi_flag') ? '1' : '0') );
        }
    }