Welcome to the Treehouse Community

The Treehouse Community is a meeting place for developers, designers, and programmers of all backgrounds and skill levels to get support. Collaborate here on code errors or bugs that you need feedback on, or asking for an extra set of eyes on your latest project. Join thousands of Treehouse students and alumni in the community today. (Note: Only Treehouse students can comment or ask questions, but non-students are welcome to browse our conversations.)

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and a supportive community. Start your free trial today.

Python Python Collections (2016, retired 2019) Slices Slice Functions

Joseph Ferrero
Joseph Ferrero
1,308 Points

No idea why my code is working, I have tested it and it worked fine.

This seems to be ok, but its not passing, what am I doingg wrong?

slices.py
def first_4(iterable):
    return(iterable[:4])

def first_and_last_4(iterable):
    return iterable[:4] + iterable[-4:]

def odds(iterable):
    return(iterable[1::2])

def reverse_evens(iterable):
    return(iterable[::-2])

1 Answer

Brian Polonia
Brian Polonia
25,139 Points

Here is my answer, it is the same as yours except I added a conditional to the last function (I'll explain below) and I removed the parenthesis from the return statements.

def first_4(iterable):  # your original code - parenthesis on return statement
    return iterable[:4]

def first_and_last_4(iterable):  # your original code
    return iterable[:4] + iterable[-4:]

def odds(utterable):  # your original code - parenthesis on return statement
    return iterable[1::2]


# Since we want to return only the even indices going backwards
# we check if the length of the iterable is even because this affects 
# whether the starting point should be [-2] or [-1] determining that
# your starting index is even. Then, as you were doing already, use a -2 step.

def reverse_evens(iterable):
    if len(iterable) % 2 == 0:
        return iterable[-2::-2]
    return iterable[-1::-2]

I hope this helps.

  • BP