public async Task <Unit> Handle(TransferCommand request, CancellationToken cancellationToken)
        {
            var transaction = await _transactionsTable.GetByIdAsync(request.TransactionId);

            var writeOffAccount = await _accountsTable.GetAsync(transaction.WriteOffAccount, transaction.UserId);

            ValidateWriteOffAccount(writeOffAccount, transaction);

            var destinationAccount = await _accountsTable.GetByIdAsync(transaction.DestinationAccount);

            ValidateDestinationAccount(destinationAccount, transaction);

            writeOffAccount.Balance     -= transaction.Amount;
            writeOffAccount.LastModified = DateTime.UtcNow;

            destinationAccount.Balance     += transaction.Amount;
            destinationAccount.LastModified = DateTime.UtcNow;

            await _accountsTable.UpdateAsync(writeOffAccount);

            await _accountsTable.UpdateAsync(destinationAccount);

            return(Unit.Value);
        }