{"ast_node_type":"variable","tokens":[{"end":73,"kind":"keyword","start":0,"text":"let"}]}
        let sup = self.type_checker.universal_regions.to_region_vid(sup);
        let sub = self.type_checker.universal_regions.to_region_vid(sub);
        self.type_checker.constraints.outlives_constraints.push(OutlivesConstraint {