code: def test_df_transform(self, daskify):
      frame = df
      if not daskify:
          frame = frame.compute()
      a = dpp.PolynomialFeatures(preserve_dataframe=True)
      b = dpp.PolynomialFeatures()
      c = spp.PolynomialFeatures()
  
      res_df = a.fit_transform(frame)
      res_arr = b.fit_transform(frame)
      res_c = c.fit_transform(frame)
  
      if daskify:
          res_pandas = a.fit_transform(frame.compute())
          assert dask.is_dask_collection(res_df)
          assert dask.is_dask_collection(res_arr)
          assert_eq_df(res_df, res_pandas)
      assert_eq_ar(res_df.values, res_c)
      assert_eq_ar(res_df.values, res_arr)
  
imports: from copy import copy
  import dask
  import dask.array
  import dask.dataframe
  import numpy
  import pandas
  import pandas.testing
  import pytest
  import sklearn.preprocessing
  from dask import compute
  from dask.array.utils import assert_eq
  from dask.dataframe.utils import assert_eq
  from pandas.api.types import is_categorical_dtype, is_object_dtype
  from sklearn.exceptions import NotFittedError
  import dask_ml.preprocessing
  from dask_ml.datasets import make_classification
  from dask_ml.utils import assert_estimator_equal
label_desc: Use image node_id 6 for calling the TestPolynomialFeatures obj's underlying member method code with example usage: obj.test_df_transform(daskify) without return types