public async Task <ActionResult <IEnumerable <SubjectDto> > > GetTimeTableGroupAsync(string groupName)
        {
            var group = _rozkladRepository.GetGroupByName(groupName);

            if (group == null)
            {
                return(NotFound());
            }

            var lessons = await _rozkladRepository.GetLessonsForGroupAsync(group.Id);

            return(Ok(lessons));
        }