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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 new_note_track(env, synth):
 """ Audio track with the frequencies. Parameters env: Envelope Stream (which imposes the duration). synth: One-argument function that receives a frequency (in rad/sample) and returns a Stream instance (a synthesized note). Returns ------- Endless Stream instance that joins synthesized notes. """

  list_env = list(env)
  return chain.from_iterable(synth(freq) * list_env for freq in freq_gen())