code: def test_none():
      train = Dataset(
          pd.DataFrame(data={"cat": ["a", "b", "c"]}),
          cat_features=["cat"],
      )
      test = Dataset(
          pd.DataFrame(data={"cat": ["a", "b", "c", None]}),
          cat_features=["cat"],
      )
      result = NewCategoryTrainTest().run(train, test).value
      assert_that(max(result["# New Categories"]), equal_to(0))
  
imports: import pandas
  from hamcrest import assert_that, calling, close_to, equal_to, greater_than, has_items, has_length, raises
  from deepchecks.core.errors import DeepchecksValueError
  from deepchecks.tabular.checks.train_test_validation import NewCategoryTrainTest
  from deepchecks.tabular.dataset import Dataset
  from tests.base.utils import equal_condition_result
label_desc: Use image node_id 11 for calling a global function with example usage: test_none() without return types