Yep. If anyone is here because they're curious about the FFT, you'd do better to start with a DFT implementation (identical to FFT, just a slower algo), most of which are tiny enough to fit on a postcard. C source code behind popular Python FFT versions are elsewhere on GitHub (ie: try Numpy or Scipy repo)
https://github.com/fotisk07/Fourier-Transform/blob/master/ut...