code: def test_df_key_hashable(df):
      """Raise error if df exists and df_key is not Hashable."""
      with pytest.raises(TypeError):
          expand_grid(df, df_key=["a"], others={"y": [5, 4, 3, 2, 1]})
  
imports: from functools import reduce
  import numpy
  import pandas
  import pytest
  from hypothesis import given, settings
  from pandas.testing import assert_frame_equal
  import janitor
  from janitor.functions.expand_grid import expand_grid
  from janitor.testing_utils.strategies import categoricaldf_strategy, df_strategy
label_desc: Use image node_id 5 for calling a global function with example usage: test_df_key_hashable(df) without return types