docstr: test inverse_transform with Nan in training expecting Nan_Onehot returned result
docstr_tok: ["test","inverse_transform","with","Nan","in","training","expecting","Nan_Onehot","returned","result"]
code: def test_inverse_transform_20(self):
      """
      test inverse_transform with Nan in training expecting Nan_Onehot returned result
      """
      train = pd.DataFrame({"city": ["chicago", np.nan]})
      enc = ce.OneHotEncoder(
          handle_missing="value", handle_unknown="value"
      )
      result = enc.fit_transform(train)
      original = inverse_transform(result, enc)
      pd.testing.assert_frame_equal(train, original)
  
imports: import unittest
  import pandas
  import numpy
  import category_encoders
  import catboost
  import lightgbm
  import xgboost
  from shapash.utils.transform import inverse_transform, apply_preprocessing, get_col_mapping_ce
  from sklearn.ensemble import GradientBoostingClassifier
label_desc: Use image node_id 20 for calling the TestInverseTransformCaterogyEncoder obj's underlying member method code with example usage: obj.test_inverse_transform_20() without return types