Determining the unmatched portion of a string using a regex in Python

Question

Suppose I have a string \"a foobar\" and I use \"^a\\s*\" to match \"a \".

Is there a way to easily get \"foobar\" returned? (What was NOT matched)

I want to

Answer 1

>>> import re
>>> re.sub("87\s*", "", "87 foo 87 bar")
'foo bar'