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Minor improvements to the docs for itertools.tee() (pythongh-119135)
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rhettinger authored May 18, 2024
1 parent 31a28cb commit 81c3130
Showing 1 changed file with 11 additions and 10 deletions.
21 changes: 11 additions & 10 deletions Doc/library/itertools.rst
Original file line number Diff line number Diff line change
Expand Up @@ -698,18 +698,19 @@ 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
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