public void Update(DateTime gigDateTime, string gigVenue, byte gigGenre)
{
var notification = Notification.gigUpdated(this, this.DateTime, this.Venue);
this.DateTime = gigDateTime;
this.Venue = gigVenue;
this.GenreId = gigGenre;
foreach (var attendee in Attendances.Select(a => a.Attendee))
{
attendee.Notify(notification);
}
}