code: def test_groupby_max_datetime64(self):
      # GH 5869
      # datetimelike dtype conversion from int
      df = DataFrame({"A": Timestamp("20130101"), "B": np.arange(5)})
      # TODO: can we retain second reso in .apply here?
      expected = (
          df.groupby("A")["A"].apply(lambda x: x.max()).astype("M8[s]")
      )
      result = df.groupby("A")["A"].max()
      tm.assert_series_equal(result, expected)
  
imports: from datetime import datetime, timedelta
  import numpy
  import pytest
  import pytz
  import pandas
  from pandas import DataFrame, DatetimeIndex, Index, MultiIndex, Series, Timestamp, date_range, offsets
  import pandas._testing
  from pandas.core.groupby.grouper import Grouper
  from pandas.core.groupby.ops import BinGrouper
label_desc: Use image node_id 15 for calling the TestGroupBy obj's underlying member method code with example usage: obj.test_groupby_max_datetime64() without return types