public SessionDetail(
     string id, string title, string details, DateTime startingOn, Speaker speaker,
     ICollection<SessionDetail> mySessions, TimeSpan? length = null)
 {
     _mySessions = mySessions;
     Id = id;
     Speaker = speaker;
     Title = title;
     Details = details;
 }
        public SpeakerDetailPage(Speaker speaker)
        {
            _speaker = speaker;            
            Padding = new Thickness(20);
            BindingContext = speaker;
            
            _deleteCommand =  new Command(() => {
                                             App.speakers.Remove(_speaker);
                                             Navigation.PopAsync();
                                         });

            // Add the controls to a StackLayout 
            Content = CreateSpeakerDetailPage();
        }