Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

Python Python Collections (Retired) Slices Slice Functions

List Slicing

Why does this not work:

def first_and_last_4(iterable):
  return iterable[:4].extend(iterable[-4:])

1 Answer

Kenneth Love
Kenneth Love
Treehouse Guest Teacher

slicing creates a new list in memory, while .extend() expects to work on a list in-place. I'm pretty sure those two are just not compatible with each other.

You can, however, concatenate two slices with +.

Thank you very much :D