code: def test_get_dummies_with_nan():
      df = cudf.DataFrame(
          {"a": cudf.Series([1, 2, np.nan, None], nan_as_null=False)}
      )
  
      expected = pd.get_dummies(
          df.to_pandas(nullable=True), dummy_na=True, columns=["a"]
      )
  
      with pytest.warns(FutureWarning):
          actual = cudf.get_dummies(df, dummy_na=True, columns=["a"])
  
      assert_eq(expected, actual)
  
file_path: cudf/python/cudf/cudf/tests/test_onehot.py
imports: from string import ascii_lowercase
  import numpy
  import pandas
  import pytest
  import cudf
  from cudf.testing._utils import assert_eq
label_desc: Use image node_id 5 for calling a global function with example usage: test_get_dummies_with_nan() without return types