code: def hertz_to_mel(frequencies_hertz):
      """Converts frequencies in `frequencies_hertz` in Hertz to the mel scale."""
      return _MEL_HIGH_FREQUENCY_Q * np.log(
          1.0
          + (np.array(frequencies_hertz) / _MEL_BREAK_FREQUENCY_HERTZ)
      )
  
file_path: magenta/magenta/models/gansynth/lib/spectral_ops.py
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import numpy
  import tensorflow.compat.v1
label_desc: Use image node_id 2 for calling a global function with example usage: hertz_to_mel(frequencies_hertz) and returns: unknown