Filtering out certain bytes in python

Question

I\'m getting this error in my python program: ValueError: All strings must be XML compatible: Unicode or ASCII, no NULL bytes or control characters

This

Answer 1

I think this is harsh/overkill and it seems painfully slow, but my program is still quick and after struggling to comprehend what was going wrong (even after I attempted to implement @John's cleaned_string implementation), I just adapted his answer to purge ASCII-unprintable using the following (Python 2.7):

from curses import ascii
def clean(text):
    return str(''.join(
            ascii.isprint(c) and c or '?' for c in text
            )) 

I'm not sure what I did wrong with the better option, but I just wanted to move on...