public async Task AddGroup(Group group)
        {
            var storageGroup = _storageGroupMapper.Map(group);
            await _storage.Groups.AddAsync(storageGroup);

            await _storage.SaveChangesAsync();
        }
        public async Task UpdateGroup(Group group)
        {
            var storageGroupToUpdate = await _storage.GetGroups().FirstAsync(g => g.Id == group.Id);

            if (storageGroupToUpdate == null)
            {
                throw new GroupsNotFoundException(group.Id);
            }
            _storageGroupMapper.Map(group, storageGroupToUpdate);
            _storage.Update(storageGroupToUpdate);
            await _storage.SaveChangesAsync();
        }