code: def testHertzToMel(self, freqs):
      mel = spectral_ops.hertz_to_mel(freqs)
      hz = spectral_ops.mel_to_hertz(mel)
      self.assertAllClose(hz, freqs)
  
file_path: magenta/magenta/models/gansynth/lib/spectral_ops_test.py
imports: from absl.testing import parameterized
  from magenta.models.gansynth.lib import spectral_ops
  import numpy
  import tensorflow.compat.v1
label_desc: Use image node_id 1 for calling the SpectralOpsTest obj's underlying member method code with example usage: obj.testHertzToMel(freqs) without return types