code: def example_reading_spec(self):
      data_fields = {
          "inputs": tf.VarLenFeature(tf.int64),
          "targets": tf.VarLenFeature(tf.int64),
          "floats": tf.VarLenFeature(tf.float32),
      }
      data_items_to_decoders = None
      return (data_fields, data_items_to_decoders)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import os
  import tempfile
  import numpy
  from six.moves import range
  from tensor2tensor.data_generators import generator_utils
  from tensor2tensor.data_generators import problem
  from tensor2tensor.layers import modalities
  from tensor2tensor.utils import data_reader
  from tensor2tensor.utils import registry
  import tensorflow.compat.v1
  from tensorflow.compat.v1 import estimator
label_desc: Use image node_id 4 for calling the TestProblem obj's underlying member method code with example usage: obj.example_reading_spec() and returns: data_fields,  data_items_to_decoders