static void Main(string[] args)
{
var sub = new Subject();
var observerA = new Observer("Observer Dave");
var observerB = new Observer("Observer Lisa");
sub.Subscribe(observerA);
sub.Subscribe(observerB);
for (int i = 0; i < 10; i++)
{
sub.SendMessage($"Message nr. {i}");
}
sub.NothingMoreToWrite();
}