// the approach below is VERY similar to how the FactoryState class reacts to
// Events to update the state of the FactoryAggregate itself
public void When(FactoryOpened e)
{
Factories[e.Id] = new FactoryInfo();
}
// announcements inside the factory that we react to and realize WHEN thisEventTypeHappened happens
public void When(FactoryOpened theEvent)
{
Id = theEvent.Id;
}