States&Cache
This is the example of how to override methods(hooks) to cache data in memory on instance attrs.
Caching and removing from cache confirmations work fine, but, unfortunately, there is pitfalls with tradeoffers.
There is no way to handle full lifecycle of tradeoffers without periodically poll changes from steam web api
(good one idea is for trigger filling trades with get_notifications
client method).
But I hope I do some of this in near future in other project which will be more suitable for trading and be middle-high layer over of and based on this project like DoctorMcKay/node-steam-tradeoffer-manager on DoctorMcKay/node-steam-user.
Or not, who knows 😶
Where is hooks
To see where hooks were called check TradeMixin and ConfirmationMixin