code: def test_append_dtype_coerce(self, sort):
      # GH 4993
      # appending with datetime will incorrectly convert datetime64
  
      df1 = DataFrame(
          index=[1, 2],
          data=[
              dt.datetime(2013, 1, 1, 0, 0),
              dt.datetime(2013, 1, 2, 0, 0),
          ],
          columns=["start_time"],
      )
      df2 = DataFrame(
          index=[4, 5],
          data=[
              [
                  dt.datetime(2013, 1, 3, 0, 0),
                  dt.datetime(2013, 1, 3, 6, 10),
              ],
              [
                  dt.datetime(2013, 1, 4, 0, 0),
                  dt.datetime(2013, 1, 4, 7, 10),
              ],
          ],
          columns=["start_time", "end_time"],
      )
  
      expected = concat(
          [
              Series(
                  [
                      pd.NaT,
                      pd.NaT,
                      dt.datetime(2013, 1, 3, 6, 10),
                      dt.datetime(2013, 1, 4, 7, 10),
                  ],
                  name="end_time",
              ),
              Series(
                  [
                      dt.datetime(2013, 1, 1, 0, 0),
                      dt.datetime(2013, 1, 2, 0, 0),
                      dt.datetime(2013, 1, 3, 0, 0),
                      dt.datetime(2013, 1, 4, 0, 0),
                  ],
                  name="start_time",
              ),
          ],
          axis=1,
          sort=sort,
      )
      result = df1._append(df2, ignore_index=True, sort=sort)
      if sort:
          expected = expected[["end_time", "start_time"]]
      else:
          expected = expected[["start_time", "end_time"]]
  
      tm.assert_frame_equal(result, expected)
  
imports: import datetime
  from itertools import combinations
  import dateutil
  import numpy
  import pytest
  import pandas
  from pandas import DataFrame, Index, Series, Timestamp, concat, isna
  import pandas._testing
label_desc: Use image node_id 13 for calling the TestAppend obj's underlying member method code with example usage: obj.test_append_dtype_coerce(sort) without return types