static void Main()
        {
            EventsRepository eventsRepository = new EventsRepository();
              while (true)
              {
            Console.WriteLine("Pick option:");
            string[] options = new[] { "a - todo", "l - list events" };
            foreach (var option in options)
            {
              Console.WriteLine(option);
            }

            string chosenOption = Console.ReadLine();
            if (chosenOption == "a")
            {
              DateSpan schedule = DateSpanReader.PromptForDateSpan();
              Console.Write("Title: ");
              string title = Console.ReadLine();
              CalendarEvent calendarEvent = new CalendarEvent(schedule, title);
              eventsRepository.AddEvent(calendarEvent);
            }
            else if (chosenOption == "l")
            {
              CalendarEvent[] calendarEvents = eventsRepository.GetEvents(DateSpan.Max);
              foreach (var calendarEvent in calendarEvents)
              {
            Console.WriteLine(calendarEvent);
              }
            }
              }
        }
        public void AddEvent(CalendarEvent eventToAdd)
        {
            IList<CalendarEvent> allEvents = GetEvents(DateSpan.Max).ToList();
              allEvents.Add(eventToAdd);

              using (Stream s = File.OpenWrite(FileName))
              {
            _binaryFormatter.Serialize(s, allEvents.ToArray());
              }
        }