code: def test_negative_step(slice_test_grouped):
      # Test for error on negative slice step
  
      with pytest.raises(ValueError, match="Invalid step"):
          slice_test_grouped.nth(slice(None, None, -1))
  
imports: import numpy
  import pytest
  import pandas
  from pandas import DataFrame, Index, MultiIndex, Series, Timestamp, isna
  import pandas._testing
label_desc: Use image node_id 34 for calling a global function with example usage: test_negative_step(slice_test_grouped) without return types