def test_interface_on_change(self): ManagedUserSet().on_change({1, 2}, {3, 4})
def test_interface_on_discard(self): ManagedUserSet().on_discard('val')
def test_interface_on_clear(self): ManagedUserSet().on_clear()
def test_interface_on_add(self): ManagedUserSet().on_add("val")