wait method
duration of the lane's clock, then a settle so what the wait released
is applied.
Implementation
Future<DriveStep> wait(Duration duration, {Duration? settle}) async {
var watch = Stopwatch()..start();
await lane.elapse(duration);
var result = await lane.settle(settle ?? settleBudget);
return DriveStep(verb: 'wait', settle: result, elapsed: watch.elapsed);
}