{"ast_node_type":"other","tokens":[{"end":75,"kind":"keyword","start":0,"text":"ty::Region::new_var(infcx.tcx,"}]}
                    ty::Region::new_var(infcx.tcx, typeck.to_region_vid(r))
                fold_regions(infcx.tcx, (opaque_type_key, hidden_type), |r, _| {
                });