From 1a5e2fd0f0bd90260eeac64742fe6bfcff80a5fa Mon Sep 17 00:00:00 2001
From: Leonardo de Moura <leonardo@microsoft.com>
Date: Tue, 20 Oct 2020 13:34:01 -0700
Subject: [PATCH] chore: move to new frontend

---
 src/Std/Data/Stack.lean | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/Std/Data/Stack.lean b/src/Std/Data/Stack.lean
index 7a8c0d7c22..3fc75b1023 100644
--- a/src/Std/Data/Stack.lean
+++ b/src/Std/Data/Stack.lean
@@ -1,3 +1,4 @@
+#lang lean4
 /-
 Copyright (c) 2019 Microsoft Corporation. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.