code: def test_difference_identity(self, index, sort):
      first = index[5:20]
      first.name = "name"
      result = first.difference(first, sort)
  
      assert len(result) == 0
      assert result.name == first.name
  
imports: from datetime import datetime
  import operator
  import numpy
  import pytest
  from pandas._libs import lib
  from pandas.core.dtypes.cast import find_common_type
  from pandas import CategoricalDtype, CategoricalIndex, DatetimeTZDtype, Index, MultiIndex, PeriodDtype, RangeIndex, Series, Timestamp
  import pandas._testing
  from pandas.api.types import is_signed_integer_dtype, pandas_dtype
label_desc: Use image node_id 12 for calling the TestSetOpsUnsorted obj's underlying member method code with example usage: obj.test_difference_identity(index, sort) without return types