Fix typo and add a module prefix (GH-28401)

(cherry picked from commit 80d9ff1)

Co-authored-by: Raymond Hettinger <[email protected]>

Author: miss-islington

Doc/library/itertools.rst

@@ -821,14 +821,14 @@ which incur interpreter overhead.
 
    def triplewise(iterable):
        "Return overlapping triplets from an iterable"
-       # pairwise('ABCDEFG') -> ABC BCD CDE DEF EFG
+       # triplewise('ABCDEFG') -> ABC BCD CDE DEF EFG
        for (a, _), (b, c) in pairwise(pairwise(iterable)):
            yield a, b, c
 
    def sliding_window(iterable, n):
        # sliding_window('ABCDEFG', 4) -> ABCD BCDE CDEF DEFG
        it = iter(iterable)
-       window = deque(islice(it, n), maxlen=n)
+       window = collections.deque(islice(it, n), maxlen=n)
        if len(window) == n:
            yield tuple(window)
        for x in it: