code: def test_insert_non_castable_str(self):
      idx = timedelta_range("1day", "3day")
  
      result = idx.insert(0, "foo")
  
      expected = Index(["foo"] + list(idx), dtype=object)
      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 6 for calling the TestTimedeltaIndexInsert obj's underlying member method code with example usage: obj.test_insert_non_castable_str() without return types