code: def test_slice_with_negative_step(index):
      keystr1 = str(index[9])
      keystr2 = str(index[13])
  
      ser = Series(np.arange(20), index)
      SLC = IndexSlice
  
      for key in [keystr1, index[9]]:
          tm.assert_indexing_slices_equivalent(
              ser, SLC[key::-1], SLC[9::-1]
          )
          tm.assert_indexing_slices_equivalent(
              ser, SLC[:key:-1], SLC[:8:-1]
          )
  
          for key2 in [keystr2, index[13]]:
              tm.assert_indexing_slices_equivalent(
                  ser, SLC[key2:key:-1], SLC[13:8:-1]
              )
              tm.assert_indexing_slices_equivalent(
                  ser, SLC[key:key2:-1], SLC[0:0:-1]
              )
  
imports: from datetime import timedelta
  import re
  import numpy
  import pytest
  from pandas.errors import IndexingError
  from pandas import NA, DataFrame, Index, IndexSlice, MultiIndex, NaT, Series, Timedelta, Timestamp, concat, date_range, isna, period_range, timedelta_range
  import pandas._testing
label_desc: Use image node_id 22 for calling a global function with example usage: test_slice_with_negative_step(index) without return types