text: from datetime import datetime
  
  import numpy as np
  
  import pandas as pd
  import pandas._testing as tm
  
  
  def test_drop_duplicates_series_vs_dataframe():
      # GH 14192
      df = pd.DataFrame(
          {
              "a": [1, 1, 1, "one", "one"],
              "b": [2, 2, np.nan, np.nan, np.nan],
              "c": [3, 3, np.nan, np.nan, "three"],
              "d": [1, 2, 3, 4, 4],
              "e": [
                  datetime(2015, 1, 1),
                  datetime(2015, 1, 1),
                  datetime(2015, 2, 1),
                  pd.NaT,
                  pd.NaT,
              ],
          }
      )
      for column in df.columns:
          for keep in ["first", "last", False]:
              dropped_frame = df[[column]].drop_duplicates(keep=keep)
              dropped_series = df[column].drop_duplicates(keep=keep)
              tm.assert_frame_equal(dropped_frame, dropped_series.to_frame())
  