Function settle_assignment 

pub fn settle_assignment(p: &mut Pending, f: &Facts, after: u64) -> bool

An assignment is a reason a thread keeps too, so an issue thread that began with one says so on every later comment. On an issue only an assignment of the viewer made after after, where listening began or the newest assignment spar already judged there, asks for a run, and only while the viewer is still assigned; any other is only something happening on a thread the viewer is part of. True when it was.