code: def test_hash():
      class Hashable:
          def __init__(self, value):
              self.value = value
  
          def __hash__(self):
              return self.value
  
      class Unhashable:
          __hash__ = None
  
      assert m.hash_function(Hashable(42)) == 42
      with pytest.raises(TypeError):
          m.hash_function(Unhashable())
  
imports: import contextlib
  import sys
  import types
  import pytest
  import env
  from pybind11_tests import detailed_error_messages_enabled
  from pybind11_tests import pytypes
label_desc: Use image node_id 29 for calling a global function with example usage: test_hash() and returns: self