def METHOD_NAME():
    class Hashable(object):
        def __init__(self, value):
            self.value = value
        def __hash__(self):
            return self.value
    class Unhashable(object):
        __hash__ = None
    assert m.hash_function(Hashable(42)) == 42
    with pytest.raises(TypeError):
        m.hash_function(Unhashable())