re.sub with a .group() - Unable to replace in python

Question

With Python, I am trying to use re.sub to replace some items in svg_text

Expected Output: Substitute RoundShapes_group_match.group() with classes_removed_text in svg_text

Actual Output: svg_text stays the same -- RoundShapes_group_match.group() remains unchanged

Here is the code. I know people suggest lxml but I can't get that to work either and would still like to figure out why the re.sub isn't working.

I think it has to do with the RoundShapes_group_match.group() because even if I try to replace with ' ' instead of classes_removed_text it doesn't work.

Question:

1. Is re.sub not able to find a.group() or.group(0) string?

My python spacing is correct, and it is not throwing errors... it doesn't look correct on Stack Overflow though...

import re

def remove_RoundShapes_group_classes(svg_text):
    """
    Within <g id="RoundShapes"> and before SquareShapes, remove all path class names.  Do not modify class names
    in other groups outside of RoundShapes.
    """
    # RoundShapes_group_match = re.search(r"""<g\s+id\s*=\s*"\S*?RoundShapes.*?</g>""", svg_text, flags=re.I | re.DOTALL)
    # Change to SquareShapes to search to next group
    RoundShapes_group_match = re.search(r"""<g\s+id\s*=\s*"\S*?RoundShapes.*?SquareShapes""", svg_text,
                                        flags=re.I | re.DOTALL)
    
    if RoundShapes_group_match is None:
        print("Could not find the RoundShapes group.", file=stderr)
        return svg_text
    
    classes_removed_text = re.sub(r'''class\s*=\s*".*?"''', '', RoundShapes_group_match.group(), flags=re.I)
    # print(classes_removed_text)
    
    RoundShapes_to_replace = (RoundShapes_group_match.group(0))
    
    ##RoundShapes_group_match.group() is what is not working.  Are there extra returns?
    svg_text = re.sub(RoundShapes_group_match.group(), classes_removed_text, svg_text, 1)
    return svg_text

Answer 1

I don't know why this resolved the issue, but instead of using re.sub I used replace

svg_text = svg_text.replace(RoundShapes_group_match.group(0), classes_removed_text)
return svg_text

It now works!