mod from_hex_len {    use git_hash::Kind;     #[test]    fn some_sha1() {        assert_eq!(Kind::from_hex_len(0), Some(Kind::Sha1));        assert_eq!(Kind::from_hex_len(10), Some(Kind::Sha1));        assert_eq!(Kind::from_hex_len(20), Some(Kind::Sha1));        assert_eq!(Kind::from_hex_len(40), Some(Kind::Sha1));    }     #[test]    fn none_if_there_is_no_fit() {        assert_eq!(Kind::from_hex_len(65), None);    }}