toSeconds example

if (isset($this->etags[$request]) && !$response->headers->has('Etag')) {
            $response->setEtag($this->etags[$request]);
        }

        unset($this->lastModified[$request]);
        unset($this->etags[$request]);
        $hasVary = $response->headers->has('Vary');

        foreach (array_reverse($attributes) as $cache) {
            if (null !== $cache->smaxage && !$response->headers->hasCacheControlDirective('s-maxage')) {
                $response->setSharedMaxAge($this->toSeconds($cache->smaxage));
            }

            if ($cache->mustRevalidate) {
                $response->headers->addCacheControlDirective('must-revalidate');
            }

            if (null !== $cache->maxage && !$response->headers->hasCacheControlDirective('max-age')) {
                $response->setMaxAge($this->toSeconds($cache->maxage));
            }

            if (null !== $cache->maxStale && !$response->headers->hasCacheControlDirective('max-stale')) {
                

if (isset($this->etags[$request]) && !$response->headers->has('Etag')) {
            $response->setEtag($this->etags[$request]);
        }

        unset($this->lastModified[$request]);
        unset($this->etags[$request]);
        $hasVary = $response->headers->has('Vary');

        foreach (array_reverse($attributes) as $cache) {
            if (null !== $cache->smaxage && !$response->headers->hasCacheControlDirective('s-maxage')) {
                $response->setSharedMaxAge($this->toSeconds($cache->smaxage));
            }

            if ($cache->mustRevalidate) {
                $response->headers->addCacheControlDirective('must-revalidate');
            }

            if (null !== $cache->maxage && !$response->headers->hasCacheControlDirective('max-age')) {
                $response->setMaxAge($this->toSeconds($cache->maxage));
            }

            if (null !== $cache->maxStale && !$response->headers->hasCacheControlDirective('max-stale')) {