message: vote -> unit
diff: @@ -304,7 +304,7 @@ impl<I: NodeIdT, C: Context + 'static> HighwayProtocol<I, C> {
  // register the proposal before the meter is aware that a new round has started, and it
  // will reject the proposal.
  if vv.is_proposal() {
  - // unwraps are safe, as if value is `Some`, this is already a vote
  + // unwraps are safe, as if value is `Some`, this is already a unit
  trace!(
  now = Timestamp::now().millis(),
  timestamp = vv.inner().timestamp().unwrap().millis(),
  