Find if ETag has changed in YoutTube

Question

I am using the latest YouTube API ie https://www.googleapis.com/youtube/v3 with the PHP client library. In an earlier version, to find out if the eTag was changed or updated for a resource, we would use the following code:

$client->getIo()->setOptions(array(
CURLOPT_HTTPHEADER => array('If-None-Match:<eTag>"')));
try {
   $response = $youtube->playlists->listPlaylists('snippet', array('id' => '6KzzScZSUrs'));
}catch (Google_Service_Exception $e) {
if (304 == $e->getCode()) {
    $response = new EmptyResponse;
} else {
    $response = null;
}

The new version is getIo()deleted. What is the alternative to using this method?