code: def testProblemHparamsModality(self):
      problem = problem_hparams.TestProblem(
          input_vocab_size=2, target_vocab_size=3
      )
      p_hparams = problem.get_hparams()
      self.assertEqual(
          p_hparams.modality["inputs"], modalities.ModalityType.SYMBOL
      )
      self.assertEqual(
          p_hparams.modality["targets"], modalities.ModalityType.SYMBOL
      )
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from absl.testing import parameterized
  import numpy
  from tensor2tensor.data_generators import algorithmic
  from tensor2tensor.data_generators import problem
  from tensor2tensor.data_generators import problem_hparams
  from tensor2tensor.layers import modalities
  from tensor2tensor.utils import hparam
  from tensor2tensor.utils import test_utils
  import tensorflow.compat.v1
  from tensorflow.compat.v1 import estimator
label_desc: Use image node_id 4 for calling the ProblemTest obj's underlying member method code with example usage: obj.testProblemHparamsModality() without return types