Detect [non] regular files in python

is_regular_file.py

#!/usr/bin/env python
"""
$ echo "ciao" | python is_regular_file.py - <(cat comments.vim) comments.vim 
'<stdin>' is not a regular file
'/dev/fd/63' is not a regular file
'comments.vim' is a regular file
"""

import os
import sys
import stat

def is_regular_file(stream):
    return stat.S_ISREG(os.fstat(stream.fileno())[stat.ST_MODE])

if len(sys.argv) < 2:
    print "Provide file names"
else:
    for filename in sys.argv[1:]:
        s = open(filename) if filename != "-" else sys.stdin
        print "{0!r} is{1} a regular file".format(s.name, "" if is_regular_file(s) else " not")