code: def test_reverse_substitution(self):
      element = (
          "url=test/url.com,snippet_id=0",
          (
              "the patient is in the emergency room.",
              ("pt", "patient"),
              {4: ("pt", "patient"), 22: ("er", "emergency room")},
          ),
      )
      rs_results = list(
          c4_wsrs_utils.reverse_substitution(
              element, substitution_rate=1.0, min_snippet_token_len=3
          )
      )
      expected_features = c4_wsrs_utils.WSRSFeatures(
          original_snippet="the patient is in the emergency room.",
          abbreviated_snippet="the pt is in the er.",
      )
      self.assertSameElements(
          rs_results,
          [
              (
                  ("pt", "patient"),
                  ("url=test/url.com,snippet_id=0", expected_features),
              )
          ],
      )
  
file_path: datasets/tensorflow_datasets/text/c4_wsrs/c4_wsrs_utils_test.py
imports: import re
  from unittest import mock
  from absl.testing import absltest
  import numpy
  from tensorflow_datasets.text.c4_wsrs import c4_wsrs_utils
label_desc: Use image node_id 5 for calling the C4WsrsUtilsTest obj's underlying member method code with example usage: obj.test_reverse_substitution() without return types