Converting a csv to vcards in Python

Context: I wrote a simple as an answer to a problem in Unix.SE and it was suggested to me to post it here for review.

A comma separated file is generated by an application. On the first column it contains a last name, on the second a first name and on the tenth column a telephone number. For each row of this csv an vcard entry should be generated.

This was my solution:

#!/usr/bin/python

import csv
import sys

def convert(file):
    reader = csv.reader(open(file, 'rb'))

    for row in reader:
        print 'BEGIN:VCARD'
        print 'VERSION:2.1'
        print 'N:' + row[0] + ';' + row[1]
        print 'FN:' + row[1] + ' ' + row[0]
        print 'TEL;HOME;VOICE:' + row[9]
        print 'END:VCARD'

def main(args):
    if len(args) != 2:
        print "Usage:"
        print args[0] + " filename"
        return

    convert(args[1])

if __name__ == '__main__':
    main(sys.argv)

Outputting the generated vcard on stdout was fine for me, I just redirected it into an appropriate file.

Read about the with statement and ALWAYS use it with file operations

with open( somefilename, 'rb' ) as source:
    reader = csv.reader( source )
    for row in reader:
       etc.

That guarantees that the file is closed and all OS resources released.

StackExchange Code Review Q#3517, answer score: 5