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![Marius Zlota](https://secure.gravatar.com/avatar/7c604723ebee697b95c33057d1e66984?s=96&d=https%3A%2F%2Fecs-static.teamtreehouse.com%2Fassets%2Fcontent%2Fdefault_avatar-445fbbabfc8dc9188fb5967fe43322ee0c3e0dd1e10f378bf8343784af5a13eb.webp&r=pg)
Marius Zlota
8,265 PointsReverse_evens doesn't parse. It does in Workspaces
What's not right? Also tried a[-1::-2] - same result
def first_4(listy):
return listy[:4]
def first_and_last_4(listy):
return listy[:4] + listy[-4:]
def odds(a):
return a[1::2]
def reverse_evens(a):
return a[::-2]
2 Answers
![Stuart Wright](https://uploads.teamtreehouse.com/production/profile-photos/6368232/micro_footgolf.jpg)
Stuart Wright
41,119 PointsNotice that your solution will not do as the question asks if you happen to give it a list with an even number of elements.
For example if a = [1, 2, 3, 4, 5, 6]
Your code will return [6, 4, 2].
Those elements are at index 5, 3, 1 (odd).
I'm not actually sure if there's a way to solve this with one single slice statement (there might well be), but you can solve this by first getting all elements with an even index, then performing a second step to reverse those elements.
![Steven Parker](https://uploads.teamtreehouse.com/production/profile-photos/969492/micro_tool_chess_set_2.jpg)
Steven Parker
230,688 PointsYou can't do this with only a step because the iterable length may be even or odd.
So you either need to compute the start value using the length of the iterable, or you need one slice to get the even indexes and another to reverse them.
Be careful about testing a challenge in an external REPL.
If you have misunderstood the challenge, it's also very likely that you will misinterpret the results.
Marius Zlota
8,265 PointsMarius Zlota
8,265 PointsThanks