Sevnup serves as a way to hand off ownership of certain objects when a node in a hashring goes down, or another node takes ownership of the keyspace. This lets you kill nodes without losing track of the current objects it was working on. You can use it for arbitrary things, but its power comes from a recover function, which lets you implement any business logic you like on a specific key. That specific key is one that sevnup brings to your attention, because you (the node) now own it and it had not been marked as 'finished' in the previous owner's logic.Using sevnup should be simple and transparent. One only needs to teach it how to persist its data, attach it to your hash ring implementation, and tell it what to do with recovered keys when necessary.