Unity networking: how to detect when a user joins the server you are hosting?

Right now I have a Host Game button and a Join Game button. When you click the Host Game button, it shows a window saying “waiting for player to join.” When you click the Join Game button, it shows a window showing active games, and updates the list every couple seconds.

Obviously I can see when the JOINING player joins the game (and therefore load the gameplay scene), but how can I detect when that happens as the HOSTING player?

In the mono script, type something like this, it will be called whenever a player had join the server. This is C# version.

void OnPlayerConnected(NetworkPlayer player) {
        Debug.Log("Player " + playerCount + " connected from " + player.ipAddress + ":" + player.port);