public bool Save(BankAccount bankAccount)
        {
            var eventStreamId = GetEventStreamId(bankAccount.Id);

            var expectedVersion = bankAccount.StoredEventVersion == 0
                ? Option.None <int>()
                : Option.Some(bankAccount.StoredEventVersion);

            var accountSaved = _appendOnlyStore.AppendToStream(eventStreamId, bankAccount.Changes, expectedVersion);

            return(accountSaved);
        }