code: def test_sort_values_key(self):
      # GH#43666, GH#52764
      sort_order = {8: 2, 6: 0, 4: 8, 2: 10, 0: 12}
      values = RangeIndex(0, 10, 2)
      result = values.sort_values(key=lambda x: x.map(sort_order))
      expected = Index([6, 8, 4, 2, 0], dtype="int64")
      tm.assert_index_equal(result, expected, check_exact=True)
  
      # check this matches the Series.sort_values behavior
      ser = values.to_series()
      result2 = ser.sort_values(key=lambda x: x.map(sort_order))
      tm.assert_series_equal(
          result2, expected.to_series(), check_exact=True
      )
  
imports: import numpy
  import pytest
  from pandas.core.dtypes.common import ensure_platform_int
  import pandas
  from pandas import Index, RangeIndex
  import pandas._testing
label_desc: Use image node_id 41 for calling the TestRangeIndex obj's underlying member method code with example usage: obj.test_sort_values_key() without return types