code: def test_contractions(self):
      x = pd.Series(
          [
              "can't won't don't can't aren't won't don't they'd there's",
          ],
      )
  
      expected = pd.Series([6])
      actual = self.primitive().get_function()(x)
      pd.testing.assert_series_equal(
          actual, expected, check_names=False
      )
  
file_path: featuretools/featuretools/tests/primitive_tests/natural_language_primitives_tests/test_number_of_unique_words.py
imports: import numpy
  import pandas
  from featuretools.primitives import NumberOfUniqueWords
  from featuretools.tests.primitive_tests.utils import PrimitiveTestBase, find_applicable_primitives, valid_dfs
label_desc: Use image node_id 4 for calling the TestNumberOfUniqueWords obj's underlying member method code with example usage: obj.test_contractions() without return types