Function answers 

pub fn answers(class: StationarityClass) -> bool

Does a certified class make a converged, physical point the answer, ending the ladder? S, the goal; and NotSearched, which claims nothing either way and only arises on models large enough that more stages are costly. A W point is not: it admits a descent direction along some branch, and a later stage can reach an S point below it (kept_if_nothing_better). A point that is not stationary at all is a stall, and the driver moves on.