code: def extractor(filename):
      # load our audio into an array
      audio = MonoLoader(filename=filename, sampleRate=44100)()
  
      # create the pool and the necessary algorithms
      pool = Pool()
      w = Windowing()
      spec = Spectrum()
      centroid = Centroid(range=22050)
  
      # compute the centroid for all frames in our audio and add it to the pool
      for frame in FrameGenerator(audio, frameSize=1024, hopSize=512):
          c = centroid(spec(w(frame)))
          pool.add("lowlevel.centroid", c)
  
      # aggregate the results
      aggrpool = PoolAggregator(defaultStats=["mean", "stdev"])(pool)
  
      # write result to file
      YamlOutput(filename=filename + ".features.yaml")(aggrpool)
  
label_desc: Use image node_id 1 for calling a global function with example usage: extractor(filename) without return types