* `Additions` now implements `Append` and uses `Append` to implement `append()`. * `append()` logic enforces that `last_seen` values should only increase. * Test written for `append()` with `last_seen` behaviour.
* `Additions` now implements `Append` and uses `Append` to implement `append()`. * `append()` logic enforces that `last_seen` values should only increase. * Test written for `append()` with `last_seen` behaviour.