From 525e7ef80d4c9b3043b611c812bedfdf444d9bf3 Mon Sep 17 00:00:00 2001 From: Raymond Hettinger Date: Sat, 18 May 2024 01:32:34 -0500 Subject: [PATCH] Minor improvements to the docs for itertools.tee() (gh-119135) (cherry picked from commit 81c3130c51a2b1504842cb1a93732cc03ddbbd79) Co-authored-by: Raymond Hettinger --- Doc/library/itertools.rst | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) diff --git a/Doc/library/itertools.rst b/Doc/library/itertools.rst index 183aa36d927550..cf2bbf0b1ae60a 100644 --- a/Doc/library/itertools.rst +++ b/Doc/library/itertools.rst @@ -690,18 +690,19 @@ loops that truncate the stream. def tee(iterable, n=2): iterator = iter(iterable) - empty_link = [None, None] # Singly linked list: [value, link] - return tuple(_tee(iterator, empty_link) for _ in range(n)) + shared_link = [None, None] + return tuple(_tee(iterator, shared_link) for _ in range(n)) def _tee(iterator, link): - while True: - if link[1] is None: - try: - link[:] = [next(iterator), [None, None]] - except StopIteration: - return - value, link = link - yield value + try: + while True: + if link[1] is None: + link[0] = next(iterator) + link[1] = [None, None] + value, link = link + yield value + except StopIteration: + return Once a :func:`tee` has been created, the original *iterable* should not be used anywhere else; otherwise, the *iterable* could get advanced without