code: def test_Timestamp(self):
      df = pd.DataFrame(
          {
              "timestamps": {
                  0: pd.Timestamp("1997-09-03 00:00:00"),
                  1: pd.Timestamp("1997-09-03 00:00:00"),
                  2: pd.Timestamp("2000-09-03 00:00:00"),
                  3: pd.Timestamp("1997-09-03 00:00:00"),
                  4: pd.Timestamp("1999-09-04 00:00:00"),
                  5: pd.Timestamp("2001-09-03 00:00:00"),
              },
          }
      )
      enc = encoders.OrdinalEncoder(cols=["timestamps"])
      encoded_df = enc.fit_transform(df)
      expected_index = [
          pd.Timestamp("1997-09-03 00:00:00"),
          pd.Timestamp("2000-09-03 00:00:00"),
          pd.Timestamp("1999-09-04 00:00:00"),
          pd.Timestamp("2001-09-03 00:00:00"),
          pd.NaT,
      ]
      expected_mapping = pd.Series(
          [1, 2, 3, 4, -2], index=expected_index
      )
      expected_values = [1, 1, 2, 1, 3, 4]
  
      pd.testing.assert_series_equal(
          expected_mapping, enc.mapping[0]["mapping"]
      )
      self.assertListEqual(
          expected_values, encoded_df["timestamps"].tolist()
      )
  
imports: import pandas
  from unittest import TestCase
  import tests.helpers
  import numpy
  import category_encoders
label_desc: Use image node_id 11 for calling the TestOrdinalEncoder obj's underlying member method code with example usage: obj.test_Timestamp() without return types