code: def test_fit_transform_have_base_2_expect_Correct_Encoding(self):
      train = pd.Series(["a", "b", "c", "d"])
  
      result = encoders.BaseNEncoder(base=2).fit_transform(train)
  
      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 1 for calling the TestBaseNEncoder obj's underlying member method code with example usage: obj.test_fit_transform_have_base_2_expect_Correct_Encoding() without return types