public static Attendee CreateAndAddAttendee(this Meeting meeting, string email)
 {
     var atendee = new Attendee(email);
     meeting.AddAttendee(atendee);
     return atendee;
 }
 public static Attendee CreateAndAddAttendee(this Meeting meeting)
 {
     var atendee = new Attendee(Guid.NewGuid() + "[email protected]");
     meeting.AddAttendee(atendee);
     return atendee;
 }