public void ReturnBook(Guid bookId)
        {
            var book = _bookStorage.GetById(bookId);

            book.CheckIn();

            var loan = _loanStorage.GetByBookId(bookId);

            var patron = _patronStorage.GetById(loan.Patron.Id);

            patron.CheckInBook();

            loan.IsReturned = true;
        }
        public void ReturnBook(Guid bookId, Guid userId)
        {
            var book = _bookStorage.GetById(bookId, userId);

            book.CheckIn();
            _bookStorage.Update(book);

            var loan = _loanStorage.GetByBookId(bookId, userId);

            var patron = _patronStorage.GetById(loan.Patron.Id, userId);

            patron.CheckInBook();
            _patronStorage.Update(patron);

            loan.IsReturned = true;
            _loanStorage.Update(loan);
        }