code: def test_HandleUnknown_HaveOnlyKnown_ExpectSecondColumn(self):
      train = ["A", "B"]
  
      encoder = encoders.BaseNEncoder(handle_unknown="indicator")
      result = encoder.fit_transform(train)
  
      self.assertEqual(2, result.shape[0])
      self.assertListEqual([0, 1], result.iloc[0, :].tolist())
      self.assertListEqual([1, 0], result.iloc[1, :].tolist())
  
imports: import pandas
  from unittest import TestCase
  import numpy
  import category_encoders
label_desc: Use image node_id 7 for calling the TestBaseNEncoder obj's underlying member method code with example usage: obj.test_HandleUnknown_HaveOnlyKnown_ExpectSecondColumn() without return types