code: def test_append_empty_tz_frame_with_datetime64ns(self):
      # https://github.com/pandas-dev/pandas/issues/35460
      df = DataFrame(columns=["a"]).astype("datetime64[ns, UTC]")
  
      # pd.NaT gets inferred as tz-naive, so append result is tz-naive
      result = df._append({"a": pd.NaT}, ignore_index=True)
      expected = DataFrame({"a": [np.nan]}, dtype=object)
      tm.assert_frame_equal(result, expected)
  
      # also test with typed value to append
      df = DataFrame(columns=["a"]).astype("datetime64[ns, UTC]")
      other = Series({"a": pd.NaT}, dtype="datetime64[ns]")
      result = df._append(other, ignore_index=True)
      tm.assert_frame_equal(result, expected)
  
      # mismatched tz
      other = Series({"a": pd.NaT}, dtype="datetime64[ns, US/Pacific]")
      result = df._append(other, ignore_index=True)
      expected = DataFrame({"a": [pd.NaT]}).astype(object)
      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 16 for calling the TestAppend obj's underlying member method code with example usage: obj.test_append_empty_tz_frame_with_datetime64ns() without return types