Function insert

ctutils/src/ct_option.rs:803–810

()

    #[test]
    fn insert() {
        let mut example = NONE;
        assert!(example.is_none().to_bool());

        let ret = example.insert(42);
        assert_eq!(ret, &42);
        assert!(example.is_some().to_bool());
    }

    #[test]
    fn insert_if() {