From 614691a7e7683730a8032e0234b62e6e5fb61771 Mon Sep 17 00:00:00 2001
From: "Miss Islington (bot)"
 <31488909+miss-islington@users.noreply.github.com>
Date: Fri, 15 Dec 2023 00:34:00 +0100
Subject: [PATCH] [3.12] Optimize unique_justseen() recipe for a common case.
 (gh-113147) (gh-113150)

---
 Doc/library/itertools.rst | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Doc/library/itertools.rst b/Doc/library/itertools.rst
index d79f40cd05e8..15b449d65051 100644
--- a/Doc/library/itertools.rst
+++ b/Doc/library/itertools.rst
@@ -1016,6 +1016,8 @@ which incur interpreter overhead.
        "List unique elements, preserving order. Remember only the element just seen."
        # unique_justseen('AAAABBBCCDAABBB') --> A B C D A B
        # unique_justseen('ABBcCAD', str.lower) --> A B c A D
+       if key is None:
+           return map(operator.itemgetter(0), groupby(iterable))
        return map(next, map(operator.itemgetter(1), groupby(iterable, key)))
 
 
-- 
2.47.3