When I print the string, I put single quotation marks into the string.
The issue is fixed by removing the single quotation marks in the string returned.

congrats. I tried to print out the list and got the same required result. Then, I use return statement, but I still got the error:

Must work with many names: "'Bart, Lisa, Maggie, Homer & Marge'" should equal 'Bart, Lisa, Maggie, Homer & Marge'

Do you have any idea to fix the issue? Thank you

I have the same problem. I try to print it out. I think the result is correct. But I still get the problem

Must work with many names: "'Bart, Lisa, Maggie, Homer & Marge'" should equal 'Bart, Lisa, Maggie, Homer & Marge'

I don't know how to fix this. Did you fix it?