[Modify] Polish it

Example3/Chat.cs

@@ -60,6 +60,11 @@ namespace Example3
     protected override void OnOpen ()
     {
       _name = getName ();
+
+      var fmt = "{0} has logged in!";
+      var msg = String.Format (fmt, _name);
+
+      Sessions.Broadcast (msg);
     }
   }
 }