code: def test_harmonic_to_sinusoidal(self):
      f0_hz = core.midi_to_hz([80, 81, 82, 81, 80])[
          np.newaxis, :, np.newaxis
      ]
      harm_amps = np.ones(shape=(1, 5, 3))
      harm_amps /= np.sum(harm_amps, axis=-1, keepdims=True)
      amps, sin_freqs = core.harmonic_to_sinusoidal(
          10, harm_amps, f0_hz
      )
      sin_freqs = np.squeeze(sin_freqs)
      f0_hz = np.squeeze(f0_hz)
      self.assertAllClose(amps, harm_amps * 10)
      self.assertAllClose(sin_freqs[..., 0], f0_hz)
      self.assertAllClose(sin_freqs[..., 1], f0_hz * 2)
      self.assertAllClose(sin_freqs[..., 2], f0_hz * 3)
  
imports: from absl.testing import parameterized
  from ddsp import core
  import librosa
  import numpy
  from scipy import signal
  import tensorflow.compat.v2
label_desc: Use image node_id 7 for calling the UtilitiesTest obj's underlying member method code with example usage: obj.test_harmonic_to_sinusoidal() without return types