private async Task <Validation <Error, Department> > Validate(CreateDepartment create) => (ValidateDepartmentName(create), ValidateBudget(create),
public Task <Either <Error, int> > Handle(CreateDepartment request, CancellationToken cancellationToken) => Validate(request) .MapT(PersistDepartment) .Bind(v => v.ToEitherAsync());