public Monitor(ISensor sensor, IIndicator indicator)
{
_sensor = sensor ?? throw new ArgumentNullException(nameof(sensor));
_indicator = indicator ?? throw new ArgumentNullException(nameof(indicator));
_sensorSubscription = _sensor.AsObservable().ObserveOn(SynchronizationContext.Current).Subscribe(Update);
ControlCommand = new ActionCommand("", Control);
Update(_sensor.GetState());
}