code: def test_union_sort_other_incomparable(self):
      # https://github.com/pandas-dev/pandas/issues/24959
      idx = Index([1, pd.Timestamp("2000")])
      # default (sort=None)
      with tm.assert_produces_warning(RuntimeWarning):
          result = idx.union(idx[:1])
  
      tm.assert_index_equal(result, idx)
  
      # sort=None
      with tm.assert_produces_warning(RuntimeWarning):
          result = idx.union(idx[:1], sort=None)
      tm.assert_index_equal(result, idx)
  
      # sort=False
      result = idx.union(idx[:1], sort=False)
      tm.assert_index_equal(result, idx)
  
imports: from datetime import datetime
  import numpy
  import pytest
  import pandas
  from pandas import Index, Series
  import pandas._testing
  from pandas.core.algorithms import safe_sort
label_desc: Use image node_id 5 for calling the TestIndexSetOps obj's underlying member method code with example usage: obj.test_union_sort_other_incomparable() without return types