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


What is wrong with my code please?

Create a function named combiner that takes a single argument, which will be a list made up of strings and numbers.

Return a single string that is a combination of all of the strings in the list and then the sum of all of the numbers. For example, with the input ["apple", 5.2, "dog", 8], combiner would return "appledog13.2". Be sure to use isinstance to solve this as I might try to trick you.

def combiner([string, num]):
    strings = ''
    total = 0
    for i in [string, num]:
        if isinstance(i, str):
            strings += i
        elif isinstance(i, (int, float)):
            total += i
    return strings + total

1 Answer

Steven Parker
Steven Parker
230,230 Points

When the instructions say the "single argument, which will be a list made up of strings and numbers", you just need one parameter name to reference that list. Besides, even if that was valid syntax you couldn't be sure the list would always contain only two entries.

You might also need to do some conversion when combining string and number results.

Thank you Steven! Your explanation is very helpful!