def METHOD_NAME(self):
    complex_type = ClassFactory.elements(1)
    enum_1 = ClassFactory.enumeration(2)
    complex_type.attrs[0].types[0].reference = enum_1.ref
    simple_type = ClassFactory.simple_type()
    enum_2 = ClassFactory.enumeration(3)
    simple_type.attrs[0].types[0].reference = enum_2.ref
    element = ClassFactory.create(tag=Tag.ELEMENT, abstract=True)
    container = ClassContainer(config=GeneratorConfig())
    container.extend([complex_type, enum_1, enum_2, simple_type, element])
    expected = [complex_type, enum_1]
    container.filter_classes()
    self.assertEqual(expected, list(container))