class_docstr: A class for querying and converting data.
docstr: Create a specgrams helper for the dataset.
code: def make_specgrams_helper(self):
      """Create a specgrams helper for the dataset."""
      raise NotImplementedError
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from magenta.models.gansynth.lib import datasets
  from magenta.models.gansynth.lib import train_util
  from magenta.models.gansynth.lib.specgrams_helper import SpecgramsHelper
  import tensorflow.compat.v1
label_desc: Use image node_id 3 for calling the DataHelper obj's underlying member method code with example usage: obj.make_specgrams_helper() without return types