Perl's Diamond Operator in Python

I'm been a full Python convert for over a year now. Perl is just too cumbersome at times. I think the artist who draws XKCD has made the same choice. The one thing that still takes me back to Perl is the ultra-handy <> "diamond operator". You can't deny Perl's dominance when it comes to string processing. Look at this elegance:

#!/usr/bin/perl

while (<>) {
    print
}

Every time I encounter a string processing problem where I have to work with multiple files, I go back to Perl. I didn't think Python could do this. Python should have the same ability as Perl's diamond:

def diamond():
    """
    diamond()
    Pre: Nothing.
    This is my attempt to recreate the very handy diamond operator found in
    Perl, which is my only reason for still using that language.

    To use the code:
    for line in diamond():
        process(line)
    """
    import sys
    if len(sys.argv[1:]) > 0:
        for file in sys.argv[1:]:
            if file == '-':
                for line in sys.stdin:
                    yield line
            else:
                f = open(file, 'r')
                for line in f:
                    yield line
                f.close()
    else:
        for line in sys.stdin:
            yield line

What does this do? It checks the sys.argv variable for file names on the command line and iterates through each line of each file. If it can't find a file, it defaults to standard input.

Of course, before I start to write code, I should always use Google first. There exist a module called "fileinput" which does the same thing.

D'oh! Hey... it's practice.