code: def testEmptyString(self):
      test_value = constant_op.constant(
          [b"", b"I love Flume!", b"", b"O hai", b""]
      )
      expected_tokens = [
          [],
          [b"I", b"love", b"Flume!"],
          [],
          [b"O", b"hai"],
          [],
      ]
      expected_offset_starts = [[], [0, 2, 7], [], [0, 2], []]
      expected_offset_ends = [[], [1, 6, 13], [], [1, 5], []]
      tokens = self.whitespace_tokenizer.tokenize(test_value)
      self.assertAllEqual(tokens, expected_tokens)
      (
          tokens,
          starts,
          ends,
      ) = self.whitespace_tokenizer.tokenize_with_offsets(test_value)
      self.assertAllEqual(tokens, expected_tokens)
      self.assertAllEqual(starts, expected_offset_starts)
      self.assertAllEqual(ends, expected_offset_ends)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import numpy
  import tensorflow
  import tensorflow_text
  from tensorflow.lite.python import interpreter
  from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import test_util
  from tensorflow.python.ops.ragged import ragged_factory_ops
  from tensorflow.python.platform import test
  from tensorflow_text.python.ops.whitespace_tokenizer import WhitespaceTokenizer
label_desc: Use image node_id 15 for calling the WhitespaceTokenizerOpTest obj's underlying member method code with example usage: obj.testEmptyString() without return types