trait RegionExt {
// Required methods
fn early(param: &GenericParam<'_>) -> (LocalDefId, ResolvedArg);
fn late(index: u32, param: &GenericParam<'_>) -> (LocalDefId, ResolvedArg);
fn id(&self) -> Option<DefId>;
fn shifted(self, amount: u32) -> ResolvedArg;
}