Function cwt_fft 

pub fn cwt_fft<T>(
    signal: &Signal<T>,
    wavelet: &dyn ContinuousWavelet,
    scales: &[f64],
    sampling_freq: f64,
) -> Result<CWTResult<T>>
where
    T: Float + FromPrimitive + Send + Sync + SignalType + AddAssign + SubAssign + MulAssign + DivAssign + RemAssign,