class_docstr: Tests for auxiliary functions to help with parsing
  Python function arguments
class_docstr_tok: ["Tests","for","auxiliary","functions","to","help","with","parsing","Python","function","arguments"]
docstr: Test _inv_dict raises an exception if a dictionary value is unhashable
docstr_tok: ["Test","_inv_dict","raises","an","exception","if","a","dictionary","value","is","unhashable"]
code: def test_inv_dict_unhashable_key(self):
      """Test _inv_dict raises an exception if a dictionary value is unhashable"""
      test_data = {"c": 8, "d": [0, 0.65], "e": "hi", "f": None, "g": 8}
  
      with pytest.raises(TypeError, match="unhashable type"):
          pu._inv_dict(test_data)
  
imports: import functools
  import itertools
  import pytest
  import numpy
  import pennylane
  import pennylane.utils
label_desc: Use image node_id 4 for calling the TestArgumentHelpers obj's underlying member method code with example usage: obj.test_inv_dict_unhashable_key() without return types