#[derive(Clone, Debug, Eq, Hash)]
pub enum Include<T> {
    All,
    Just(T),
}

impl<T: PartialEq> PartialEq for Include<T> {
    fn eq(&self, other: &Self) -> bool {
        match self {
            Include::All => true,
            Include::Just(data) => match other {
                Include::All => true,
                Include::Just(other_data) => data == other_data,
            },
        }
    }
}

#[cfg(test)]
mod includes {
    use super::*;

    #[test]
    fn does_all_equal_evberything() {
        let a: Include<isize> = Include::All;
        let b: Include<isize> = Include::Just(5);
        let c: Include<isize> = Include::Just(7);
        assert!(a == a, "all should equal all");
        assert!(a == b, "all should equal some");
        assert!(b == a, "some should equal all");
        assert!(b == b, "same some should equal");
        assert!(b != c, "different somes do not equal");
    }
}