You don't need the extra parentheses if you wanted a cleaner oneliner

if there's an x in the string, then the input is invalid

Given a string made up of letters a, b, and/or c

good, but if input string have a "x" char this solution doesnt worked.

Cool, coudn't figure out how to pass it in one line

Didn't think about 3d var...
COOL again Thank you

Nice

Not the shortest, but ok

nice

OMG WOW !!

its less readable to me . isnt good python code meant to be easy to read

Okay. Thank you for explaining.

This works in Python 2 but not in python 3

Why is this a solution if it doesn't work?

Thanks for the explanation!
1 kyu!!
Respects (｡♡‿♡｡)