code: def test_insert_invalid_na(self):
      idx = TimedeltaIndex(["4day", "1day", "2day"], name="idx")
  
      item = np.datetime64("NaT")
      result = idx.insert(0, item)
  
      expected = Index([item] + list(idx), dtype=object, name="idx")
      tm.assert_index_equal(result, expected)
  
      # Also works if we pass a different dt64nat object
      item2 = np.datetime64("NaT")
      result = idx.insert(0, item2)
      tm.assert_index_equal(result, expected)
  
file_path: pandas/pandas/tests/indexes/timedeltas/methods/test_insert.py
imports: from datetime import timedelta
  import numpy
  import pytest
  from pandas._libs import lib
  import pandas
  from pandas import Index, Timedelta, TimedeltaIndex, timedelta_range
  import pandas._testing
label_desc: Use image node_id 3 for calling the TestTimedeltaIndexInsert obj's underlying member method code with example usage: obj.test_insert_invalid_na() without return types