Issue #10029: Fix sample code in the docs for zip().
diff --git a/Doc/library/functions.rst b/Doc/library/functions.rst
index efcac08..e97be7b 100644
--- a/Doc/library/functions.rst
+++ b/Doc/library/functions.rst
@@ -1220,11 +1220,18 @@
iterable argument, it returns an iterator of 1-tuples. With no arguments,
it returns an empty iterator. Equivalent to::
- def zip(*iterables):
- # zip('ABCD', 'xy') --> Ax By
- iterables = map(iter, iterables)
- while iterables:
- yield tuple(map(next, iterables))
+ def zip(*iterables):
+ # zip('ABCD', 'xy') --> Ax By
+ sentinel = object()
+ iterables = [iter(it) for it in iterables]
+ while iterables:
+ result = []
+ for it in iterables:
+ elem = next(it, sentinel)
+ if elem is sentinel:
+ return
+ result.append(elem)
+ yield tuple(result)
The left-to-right evaluation order of the iterables is guaranteed. This
makes possible an idiom for clustering a data series into n-length groups