class_docstr: Tests utility functions.
      
code: def test_truncate_seq_pair(self):
      tokens_a = [1, 2, 3]
      tokens_b = [4, 5, 6]
      utils.truncate_seq_pair(tokens_a, tokens_b, 4)
      self.assertListEqual(tokens_a, [1, 2])
      self.assertListEqual(tokens_b, [4, 5])
  
      tokens_a = [1]
      tokens_b = [2, 3, 4, 5]
      utils.truncate_seq_pair(tokens_a, tokens_b, 3)
      self.assertListEqual(tokens_a, [1])
      self.assertListEqual(tokens_b, [2, 3])
  
file_path: texar/tests/utils/utils_test.py
imports: import tempfile
  import numpy
  import tensorflow
  from texar.tf.utils import utils
  from texar.tf.data.vocabulary import Vocab
label_desc: Use image node_id 9 for calling the UtilsTest obj's underlying member method code with example usage: obj.test_truncate_seq_pair() without return types