interface Sensor {
  in void activate();
  in void deactivate();
  behaviour { 
    on activate: {}
    on deactivate: {}
  }
}
 
component Alarm1 {
  requires Sensor sensor;
  behaviour { 

  }
}

interface Siren {
  out void start();
  out void stop();
  behaviour { 
    bool b = true;
    on inevitable: {}
  }
}
  
component Alarm2 {
  provides Siren siren;
  behaviour { }
}