dan@Cairo:~$ ls -l /tmp/foo suexec.py 
-rw-------   1 root  wheel   0 Aug 20 20:41 /tmp/foo
-rwsr-sr-x   1 root  dan    53 Aug 20 20:43 suexec.py*

dan@Cairo:~$ ./suexec.py 
Traceback (most recent call last):
  File "./suexec.py", line 5, in ?
    os.unlink('/tmp/foo');
OSError: [Errno 13] Permission denied: '/tmp/foo'

dan@Cairo:~$ cat suexec.py 
#!/usr/bin/python

import os

os.unlink('/tmp/foo');