parser = OptionParser()
parser.add_option('-f', '--file', dest='filename', help=
    'write report to FILE', metavar='FILE')
parser.add_option('-q', '--quiet', action='store_false', dest='verbose',
    default=True, help="don't print status messages to stdout")
options, args = parser.parse_args()
How can I specify that some command line arguments are mandatory in Python?