We've talked elsewhere about the fact that capturing a block using the `&proc` incurs a runtime cost.  Given that, I'm thinking it would be better to pass the proc on as a normal arg, rather than `to_proc`ing it via `&` only to have it be re-reified into a `Proc` in `Procsy#initalize`.  Also, it might be worth doing the same with this method, depending on whether or not the caller has a `Proc` object already or simply passes a block.