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