public Task <Result <Unit> > Get(RegisterUserRequest key) => _createUser.Get(key) .ThenConcatWith(userId => _createGroup.Get(new CreateGroupRequest { GroupName = $"{key.Email} Personal" })) .Then(ctx => _addUserToGroup.Get(new AddUserToGroupRequest { UserId = ctx.Item1, GroupId = ctx.Item2 })) .Then(_ => new Unit());