parser.add_option('-o', help="where to send the output, file name or '-' to indicate stdout [default: %default]", default='{first file}.defs', dest='output')
parser.add_option('--words', help='interpret the input as words, not file names [default: %default]', default=False, action='store_true')
parser.add_option('--delimiter', help='delimiter between words in the files [default: %default]', default='\\n')