{"ast_node_type":"variable","tokens":[{"end":100,"kind":"keyword","start":0,"text":"let"}]}
                let kind = ty::LateParamRegionKind::from_bound(ty::BoundVar::from_usize(idx), kind);
            if let ty::BoundVariableKind::Region(kind) = bound_var {
                let r = ty::Region::new_late_param(self.infcx.tcx, self.mir_def.to_def_id(), kind);