From a1bf55e96f47938cd142bb64a5d4891d2817d931 Mon Sep 17 00:00:00 2001
From: Marco Gorelli <33491632+MarcoGorelli@users.noreply.github.com>
Date: Thu, 28 Mar 2024 16:29:44 +0000
Subject: [PATCH] add default

---
 narwhals/functions.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/narwhals/functions.py b/narwhals/functions.py
index ac443af05..02a551775 100644
--- a/narwhals/functions.py
+++ b/narwhals/functions.py
@@ -12,7 +12,9 @@
 
 
 def concat(
-    items: Iterable[DataFrame | LazyFrame], *, how: Literal["horizontal", "vertical"]
+    items: Iterable[DataFrame | LazyFrame],
+    *,
+    how: Literal["horizontal", "vertical"] = "vertical",
 ) -> DataFrame | LazyFrame:
     if how not in ("horizontal", "vertical"):
         raise NotImplementedError(