{"ast_node_type":"other","tokens":[{"end":73,"kind":"keyword","start":0,"text":"//"}]}
                    // The bound says that `r1 <= r2`; we store `r2: r1`.
                OutlivesBound::RegionSubRegion(r1, r2) => {
                    let r1 = self.universal_regions.to_region_vid(r1);