def _parser_add_duration_and_reservation(subparser, duration_required):
    """Add a 'duration' and a 'reservation' argument to subparser.

    :param subparser: subparser instance
    :param duration_required: select if duration is required or optional
    """
    subparser.add_argument('-d', '--duration', required=duration_required,
        type=int, help='experiment duration in minutes')
    subparser.add_argument('-r', '--reservation', type=int, help=
        'experiment schedule starting : seconds since 1970-01-01 00:00:00 UTC')
