code: def test_sort_index_multiindex_key_multi_level(self):
      mi = MultiIndex.from_tuples(
          [[1, 1, 3], [1, 1, 1]], names=list("ABC")
      )
      s = Series([1, 2], mi)
      backwards = s.iloc[[1, 0]]
  
      result = s.sort_index(level=["A", "C"], key=lambda x: -x)
      tm.assert_series_equal(s, result)
  
      result = s.sort_index(
          level=["A", "C"], key=lambda x: x
      )  # nothing happens
      tm.assert_series_equal(backwards, result)
  
imports: import numpy
  import pytest
  from pandas import DatetimeIndex, IntervalIndex, MultiIndex, Series
  import pandas._testing
label_desc: Use image node_id 2 for calling the TestSeriesSortIndexKey obj's underlying member method code with example usage: obj.test_sort_index_multiindex_key_multi_level() without return types