class_docstr: A class for querying and converting data.
code: def __init__(self, config):
      self._config = config
      self._dataset_name = config["dataset_name"]
      self.dataset = datasets.registry[self._dataset_name](config)
      self.specgrams_helper = self.make_specgrams_helper()
  
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 1 to create a new DataHelper object from inherited base classes: object with example: obj = DataHelper(config)