public IActionResult AddGroup([FromBody] AddGroupFiltersModel model)
        {
            bool res = _groups.AddGroup(new AddGroupModel
            {
                Name         = model.Name,
                SpecialityId = model.SpecialityId,
                TeacherId    = model.TeacherId,
                DateFrom     = Convert.ToDateTime(model.DateFrom),
                DateTo       = Convert.ToDateTime(model.DateTo)
            });

            if (res)
            {
                return(Ok(res));
            }
            else
            {
                return(BadRequest(res));
            }
        }