public async Task <IActionResult> AddTimeSlot()
        {
            var rooms = await _roomService.GetAllRoomsAsync();

            var roomNames = rooms
                            .Select(x => new SelectListItem
            {
                Text  = x.Name,
                Value = x.Id.ToString()
            }).ToList();

            var sessions = await _sessionService.GetAllSessionsAsync();

            var sessionTitles = sessions
                                .Select(x => new SelectListItem
            {
                Text  = x.Title,
                Value = x.Id.ToString()
            }).ToList();

            var possibleTimeSlots = await _timeSlotService.GetAllLegalTimeSlotsAsync();

            var strTimeSlots = possibleTimeSlots
                               .Select(x => new SelectListItem
            {
                Text  = x.ToString("G"),
                Value = x.ToString("G")
            }).ToList();

            var timeSlotBindingModel = new TimeSlotBindingModel
            {
                SessionTitles = sessionTitles,
                RoomNames     = roomNames,
                TimeSlots     = strTimeSlots
            };

            return(View(timeSlotBindingModel));
        }