See here: <https://github.com/SciNim/impulse/blob/26e25e7/impulse/fft/pocketfft.nim#L302-L339>
For now there is no high-level API because i couldn't get feedback on what people would want. It requires C++ compilation as well. I started to implement a pure Nim one but it was quite an effort and I had no time at that time.
