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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def ks_synth(freq):
 """ Synthesize the given frequency into a Stream by using a model based on Karplus-Strong. """

  ks_mem = (sum(lz.sinusoid(x * freq) for x in [1, 3, 9]) +
            lz.white_noise() + lz.Stream(-1, 1)) / 5
  return lz.karplus_strong(freq, memory=ks_mem)