public Result <Class> AssignedClass(int teacherId)
{
if (_teacherGateway.FindById(teacherId) == null)
{
return(Result.Failure <Class>(Status.BadRequest, "Unknown teacher."));
}
Class c = _classGateway.FindByTeacherId(teacherId);
if (c == null)
{
c = new Class();
}
return(Result.Success(Status.Ok, c));
}