parser.add_argument('host', nargs=1, help='ip address to lookup')
main_group = parser.add_mutually_exclusive_group()
mysql_group = main_group.add_argument_group()
main_group.add_argument('-s', '--ssh', dest='ssh', action='store_true',
    default=False, help=
    'Connect to this machine via ssh, instead of printing hostname')
mysql_group.add_argument('-m', '--mysql', dest='mysql', action='store_true',
    default=False, help=
    'Start a mysql tunnel to the host, instead of printing hostname')
main_group.add_argument('-f', '--firefox', dest='firefox', action=
    'store_true', default=False, help=
    'Start a firefox session to the remotemyadmin instance')
python argparse with dependencies