code: def test_append_frame_with_timedelta64ns_nat(self, dtype_str, val):
      # https://github.com/pandas-dev/pandas/issues/35460
      df = DataFrame({"a": pd.array([1], dtype=dtype_str)})
  
      other = DataFrame({"a": [np.timedelta64(val, "ns")]})
      result = df._append(other, ignore_index=True)
  
      expected = DataFrame(
          {"a": [df.iloc[0, 0], other.iloc[0, 0]]}, dtype=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 18 for calling the TestAppend obj's underlying member method code with example usage: obj.test_append_frame_with_timedelta64ns_nat(dtype_str, val) without return types