code: def test_HandleMissingIndicator_HaveNoNan_ExpectThirdColumn(self):
      train = pd.Series(["a", "b", "c"])
  
      result = encoders.BaseNEncoder(
          handle_missing="indicator", base=2
      ).fit_transform(train)
  
      self.assertEqual(3, 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())
  
imports: import pandas
  from unittest import TestCase
  import numpy
  import category_encoders
label_desc: Use image node_id 4 for calling the TestBaseNEncoder obj's underlying member method code with example usage: obj.test_HandleMissingIndicator_HaveNoNan_ExpectThirdColumn() without return types