Getting file extension using pattern matching in python

Question

I am trying to find the extension of a file, given its name as a string. I know I can use the function os.path.splitext but it does not work as expected in case

Answer 1

root,ext = os.path.splitext('a.tar.gz')
if ext in ['.gz', '.bz2']:
   ext = os.path.splitext(root)[1] + ext

_{Some people, when confronted with a problem, think "I know, I'll use regular expressions." Now they have two problems.}