code: def sawtooth_wave(freq0, amp0, num_pitches, sample_rate):
      freq = extend_pitch(freq0, num_pitches)
  
      mults = [
          -((-1) ** i) / (PI * i) for i in range(1, 1 + num_pitches)
      ]
      amp = extend_pitch(amp0, mults)
      waveform = oscillator_bank(freq, amp, sample_rate=sample_rate)
      return freq, amp, waveform
  
file_path: audio/examples/tutorials/additive_synthesis_tutorial.py
imports: import torch
  import torchaudio
  import matplotlib.pyplot
  from IPython.display import Audio
label_desc: Use image node_id 2 for calling a global function with example usage: sawtooth_wave(freq0, amp0, num_pitches, sample_rate) and returns: freq,  amp,  waveform