#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
pub struct VolumeIndex(usize);
impl VolumeIndex {
pub fn new(index: usize) -> Self {
debug_assert!(index <= 999, "Volume index must be <= 999");
Self(index)
}
pub fn as_number(&self) -> usize {
self.0
}
}