Hi lomkiri, you are fast as light

I'd like to install the new version of Calibre, unfortunately my OS doesn't support it.
I have modified the script because it was giving me "IndexError: no such group", but now it works fine:
Code:
def replace(match, number, file_name, metadata, dictionaries, data, functions, *args, **kwargs):
start_at = 19
n = int(match.group(1))
if n >= start_at:
return str(n-1)
return match.group(0)
Thank you very much for your support.