[Modify] Polish it

Example3/Program.cs

@@ -185,10 +185,9 @@ namespace Example3
       httpsv.Start ();
 
       if (httpsv.IsListening) {
-        Console.WriteLine (
-          "Listening on port {0}, and providing WebSocket services:",
-          httpsv.Port
-        );
+        var fmt = "Listening on port {0}, and providing WebSocket services:";
+
+        Console.WriteLine (fmt, httpsv.Port);
 
         foreach (var path in httpsv.WebSocketServices.Paths)
           Console.WriteLine ("- {0}", path);