def METHOD_NAME():
    '''Check that the _create_classes() method creates the dictionary of
    functor classes just once.
    '''
    factory = LFRicBuiltinFunctorFactory.get()
    factory._create_classes()
    assert "setval_x" in factory._builtin_functor_map
    setval_x = factory._get_builtin_class("setval_x")
    factory._create_classes()
    assert setval_x is factory._builtin_functor_map["setval_x"]
    factory._builtin_functor_map = {}