Returns the most recent entities vector saved in the timeline after removing the last steps from it. Start recording to the timeline by calling (update! screen :timeline []).
If there are 100 items saved in the timeline and (rewind! screen 1) is called, it will remove the last one and return the entities vector from the 99th item. If steps is invalid, nil is returned.
If you want to do something more complex with the timeline than a simple rewind, you can directly access it via (:timeline screen). Each item inside it is a vector containing a timestamp (seconds since the screen was first shown) and an entities vector.
Source
(defn rewind!
[{:keys [timeline update-fn!] :as screen} steps]
(when-let [[total-time entities] (get timeline (- (count timeline) steps 1))]
(update-fn! update-in [:timeline] subvec 0 (- (count timeline) steps 1))
entities))