How to use the mdns.ServiceType function in mdns

ad.start();

var browser = mdns.createBrowser(mdns.tcp('http'));

browser.on('serviceUp', function(service:MDNS.Service) {
    console.log("service up: ", service);
});
browser.on('serviceDown', function(service:MDNS.Service) {
    console.log("service down: ", service);
});

browser.start();

var r0 = mdns.tcp('http')                     // string form: _http._tcp
    , r1 = mdns.udp('osc', 'api-v1')            // string form: _osc._udp,_api-v1
    , r2 = new mdns.ServiceType('http', 'tcp')  // string form: _http._tcp
    , r3 = mdns.makeServiceType('https', 'tcp') // string form: _https._tcp
    ;

var txt_record = {
    name: 'bacon'
    , chunky: true
    , strips: 5
};
var ad:MDNS.Advertisement = mdns.createAdvertisement(mdns.tcp('http'), 4321, {txtRecord: txt_record});

var sequence = [
    mdns.rst.DNSServiceResolve()
    , mdns.rst.DNSServiceGetAddrInfo({families: [4] })
];

var browser = mdns.createBrowser(mdns.tcp('http'), {resolverSequence: sequence});