private async Task <Validation <Error, OfficeAssignment> > Validate(CreateOfficeAssignment create) => (NotEmpty(create.Location), await InstructorMustExist(create))
public Task <Validation <Error, int> > Handle(CreateOfficeAssignment request, CancellationToken cancellationToken) => Validate(request) .MapT(Persist) .Bind(v => v.Traverse(i => i));