code: func Enable(server *prpc.Server) {
  	serviceNames := append(server.ServiceNames(), "discovery.Discovery")
  	service, err := New(serviceNames...)
  	if err != nil {
  		panic(err)
  	}
  	RegisterDiscoveryServer(server, service)
  }
docs: // Enable registers a discovery service on the server.
  // It makes all currently registered services and the discovery service
  // discoverable.