Function all_acknowledged 

fn all_acknowledged(
    knowledge: &Knowledge,
    start: i64,
    acks: &BTreeMap<String, i64>,
    now: i64,
) -> bool

Whether every device that must (must_acknowledge) said it read this computer’s opening start, that very one (acks: acknowledgements): a word naming another opening, later or impossible, says nothing (M1); a word of a phone not heard here within WORD_FRESH says nothing either (N1, N2).