code: def hparams(self, defaults, model_hparams):
      hp = defaults
      hp.modality = {
          "inputs": modalities.ModalityType.SYMBOL,
          "targets": modalities.ModalityType.SYMBOL,
      }
      hp.vocab_size = {"inputs": 30, "targets": 30}
  
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 3 for calling the TestProblem obj's underlying member method code with example usage: obj.hparams(defaults, model_hparams) without return types