Fortune Street Music Renamer

import csv, os, sys

def load_tags_from(tag_file):
    tags = {}
    csv_reader = csv.reader(tag_file)
    #Skip the first row
    csv_reader.next()
    for row in csv_reader:
        original_name, song_index, tagged_name = row
        tags[original_name] = '{0} - {1}'.format(song_index, tagged_name)
    return tags

def print_usage():
    print 'Usage: python {0} (original|detailed)'.format(sys.argv[0])

def main():
    args = sys.argv[1:]
    if len(args) != 1:
        print_usage()
        return
    mode = args[0].lower()
    if mode != 'original' and mode != 'detailed':
        print_usage()
        return
    tag_file = open('tags.csv','rb')
    tags = load_tags_from(tag_file)
    #Rename the files
    if mode == 'detailed':
        for name in tags:
            old_name = name
            new_name = tags[name]
            os.rename(old_name, new_name)
    else:
        for name in tags:
            current_name = tags[name]
            original_name = name
            os.rename(current_name, original_name)

if __name__ == '__main__':
    main()