code: def test_multiline(self):
      x = pd.Series(
          [
              "@\n\t\n",
              "@mention\n @mention2\n@\n\n",
          ],
      )
  
      expected = [0.0, 2.0]
      actual = self.primitive().get_function()(x)
      np.testing.assert_array_equal(actual, expected)
  
file_path: featuretools/featuretools/tests/primitive_tests/natural_language_primitives_tests/test_number_of_mentions.py
imports: import numpy
  import pandas
  from featuretools.primitives import NumberOfMentions
  from featuretools.tests.primitive_tests.utils import PrimitiveTestBase, find_applicable_primitives, valid_dfs
label_desc: Use image node_id 3 for calling the TestNumberOfMentions obj's underlying member method code with example usage: obj.test_multiline() without return types