//REMOVES AN OBSERVER FROM THE SUBJECT
public void unregisterObserver(ATMPanel e)
{
for (int i = 0; i < observerList.Count; i++)
{
this.observerList.Remove(e);
}
}
//ADDS AN OBSERVER TO THE SUBJECT
public void registerObserver(ATMPanel e)
{
this.observerList.Add(e);
}