{"ast_node_type":"function","tokens":[{"end":93,"kind":"keyword","start":0,"text":"fn"}]}
    fn record_late_bound_vars(&mut self, hir_id: HirId, binder: Vec<ty::BoundVariableKind>) {
        if let Some(old) = self.rbv.late_bound_vars.insert(hir_id.local_id, binder) {