Function first_rule 

pub fn first_rule(attention: &Attention, person: Person) -> Rule

A rule’s first value, from your Calls row of strangers or hidden numbers as it was before the screening was apart: the closest rule that never rings where the row declined. Ringing at every hour only when it rang at every time; ringing in work and admin hours when it rang in either; voicemail otherwise (review of part 2, F2: a row that rang in leisure alone once gave ringing at night). Its layers (time for you, do-not-disturb) are no part of the screening.