public static void AddPowerUpInvoker(ItemController powerUpInvoker)
{
// add the new invoker to the list of invokers
powerUpInvokers.Add(powerUpInvoker);
// ensure that all existing listeners are added to this new invoker
foreach (UnityAction <string> listener in powerUpListeners)
{
powerUpInvoker.AddPowerUpListener(listener);
}
}
