#[derive(Debug, Copy, Clone)]
 enum ExitClass {
    Document = 1,
    Alpha = 2,
    Beta = 3,
    Gamma = 4,
}

impl std::fmt::Display for ExitClass {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
        write!(f, "{:?}", self)
    }
}