def displayText(self, value, locale):
        return ''
Invoke list_set() with extra parameter.
dataset/ETHPy150Open enthought/traitsui/traitsui/qt4/image_enum_editor.py/ImageEnumItemDelegate.displayText--crossover with--dataset/ETHPy150Open aerospike/aerospike-client-python/test/new_tests/test_list_set.py/TestListSet.test_neg_list_set_with_extra_parameter