public void AddItems()
        {
            var bank = new BankEntity
            {
                Name = "Bank Account",
                Town = "Some Town",
            };

            var customer = new CustomerEntity
            {
                Name = "customer 1",
            };

            var account1 = new BankAccountEntity
            {
                Name    = "acc1",
                Balance = 123
            };

            var account2 = new BankAccountEntity
            {
                Name    = "acc2",
                Balance = 555
            };

            bank.Customers.Add(customer);
            customer.Accounts.Add(account1);
            customer.Accounts.Add(account2);

            using (var repo = _context.BeginTransaction())
            {
                repo.Create(bank);
                repo.Create(customer);
                repo.Create(account1);
                repo.Create(account2);

                repo.Commit();
            }
        }