method != "GET") { return new Response(405, "", "", ["Allow: GET"]); } if (preg_match("<^/?$>", $req->path)) { // if the request path is an empty string or just a slash, return the supported versions $out = [ 'apiLevels' => [ 'v1-2', ] ]; return new Response(200, $out); } else { // if the URL path was anything else, the client is probably trying a version we don't support return new Response(501); } } }