Conditional construct not working in Python regex

Question

I an a newbie in python and I want to use my regex in re.sub. I tried it on regex101 and it works. Somehow when I tried to use it on my python (version 3.6) it does

Answer 1

I suppose you could do this:

import re

regex = r'(^\w*?[\t]+)'
s = 'a      bold, italic,           teletype'

def repl(match):
    s = match.group(0)
    return s.rstrip() + ', '

print(re.sub(regex,repl, s))

out

a, bold, italic,            teletype

Here we are capturing the beginning of the string through any tabs that may occur after the first word, and passing the match to a callable. The callable removes trailing tabs with rstrip and adds a trailing comma.

Note: if the first tab occurs after the first word, it's not replaced. i.e. 'a bold, italic, teletype' is left unchanged. Is that what you want?