code: def test_HandleMissingIndicator_NanNoNanInTrain_ExpectAsNanColumn(
      self,
  ):
      train = pd.Series(["a", "b", "c"])
      test = pd.Series(["a", "b", "c", np.nan])
  
      encoder = encoders.BaseNEncoder(handle_missing="indicator")
      encoder.fit(train)
      result = encoder.transform(test)
  
      self.assertEqual(4, result.shape[0])
      self.assertListEqual([0, 0, 1], result.iloc[0, :].tolist())
      self.assertListEqual([0, 1, 0], result.iloc[1, :].tolist())
      self.assertListEqual([0, 1, 1], result.iloc[2, :].tolist())
      self.assertListEqual([1, 0, 0], result.iloc[3, :].tolist())
  
imports: import pandas
  from unittest import TestCase
  import numpy
  import category_encoders
label_desc: Use image node_id 5 for calling the TestBaseNEncoder obj's underlying member method code with example usage: obj.test_HandleMissingIndicator_NanNoNanInTrain_ExpectAsNanColumn() without return types