@classmethod
def arg_qxform(cls, parser):
    """Add an `~argparse.ArgumentGroup` for Q-transform options
        """
    group = parser.add_argument_group('Q-transform options')
    group.add_argument('--plot', nargs='+', type=float, default=[0.5], help
        ='One or more times to plot')
    group.add_argument('--frange', nargs=2, type=float, help=
        'Frequency range to plot')
    group.add_argument('--qrange', nargs=2, type=float, help='Search Q range')
    group.add_argument('--nowhiten', action='store_true', help=
        'do not whiten input before transform')
