I'm getting this error message:
Oops, try again. remove_duplicates() resulted in an error: list index out of range
With the following code:
new = 
for i in range(len(zz)):
if zz[i] not in new: new.append(zz[i]) return new
I don't know how that is an error, as this code works on other shells. I don't think that the range of len(zz) should possibly give me an error... and I'm not modifying the list 'zz' at all.
Replace this line with your code.