{"ast_node_type":"variable","tokens":[{"end":48,"kind":"keyword","start":0,"text":"let"}]}
        let r_scc = self.constraint_sccs.scc(r);
    pub(crate) fn upper_bound_in_region_scc(&self, r: RegionVid, upper: RegionVid) -> bool {
        self.scc_values.contains(r_scc, upper)