public async ValueTask Handle(DefineAccount command, CancellationToken cancellationToken = default) { var optionalChart = await _chartOfAccounts.GetOptional(cancellationToken); var chart = optionalChart.HasValue ? optionalChart.Value : ChartOfAccounts.Factory(); chart.DefineAccount(new AccountName(command.AccountName !), new AccountNumber(command.AccountNumber)); if (!optionalChart.HasValue) { _chartOfAccounts.Add(chart); } }