{"ast_node_type":"variable","tokens":[{"end":90,"kind":"keyword","start":0,"text":"let"}]}
                        let actual = fold_regions(cx, actual, |re, _dbi| match re.kind() {
                            cx.type_of_opaque_hir_typeck(def_id).instantiate(cx, opaque_ty.args);
                            ty::ReErased => self.next_region_var(),