class_docstr: Base class for speech recognition problems.
code: def example_reading_spec(self):
      data_fields = {
          "waveforms": tf.VarLenFeature(tf.float32),
          "targets": tf.VarLenFeature(tf.int64),
      }
  
      data_items_to_decoders = None
  
      return data_fields, data_items_to_decoders
  
imports: import numpy
  from tensor2tensor.data_generators import audio_encoder
  from tensor2tensor.data_generators import problem
  from tensor2tensor.data_generators import text_encoder
  from tensor2tensor.layers import common_audio
  from tensor2tensor.layers import common_layers
  from tensor2tensor.layers import modalities
  from tensor2tensor.utils import metrics
  import tensorflow.compat.v1
label_desc: Use image node_id 6 for calling the SpeechRecognitionProblem obj's underlying member method code with example usage: obj.example_reading_spec() and returns: data_fields,  data_items_to_decoders