@classmethod
def arg_fft(cls, parser):
    """Add an `~argparse.ArgumentGroup` for FFT options
        """
    group = parser.add_argument_group('Fourier transform options')
    group.add_argument('--secpfft', type=float, default=1.0, help=
        'length of FFT in seconds')
    group.add_argument('--overlap', type=float, help=
        'overlap as fraction of FFT length [0-1)')
    group.add_argument('--window', type=str, default='hann', help=
        'window function to use when overlapping FFTs')
    return group
