/usr/lib/python3/dist-packages/systemfixtures/matchers.py is in python3-systemfixtures 0.6.4-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15  | import os
from testtools.matchers import (
    AfterPreprocessing,
    Equals,
)
def HasOwnership(uid, gid):
    def ownership(path):
        info = os.stat(path)
        return info.st_uid, info.st_gid
    return AfterPreprocessing(ownership, Equals((uid, gid)))
 |