#[derive(Debug)]
struct MotorImpl {
    speed: u8,
}

#[derive(Debug)]
struct SpecializedMotorImpl(MotorImpl);

impl MotorImpl {
    fn new() -> MotorImpl {
        MotorImpl { speed: 0 }
    }
}

trait Motor {
    fn run(&mut self) {
        self.set_speed(1);
    }
    fn stop(&mut self) {
        self.set_speed(0);
    }

    fn set_speed(&mut self, speed: u8);
}

impl Motor for MotorImpl {
    fn set_speed(&mut self, speed: u8) {
        self.speed = speed
    }
}

trait SpecializedMotor: Motor {
    fn run_fast(&mut self) {
        self.set_speed(2);
    }
}

impl Motor for SpecializedMotorImpl {
    fn set_speed(&mut self, speed: u8) {
        self.0.set_speed(speed)
    }
}

impl SpecializedMotor for SpecializedMotorImpl {}

fn main() {
    let mut motor = MotorImpl::new();
    let mut specialized_motor = SpecializedMotorImpl(MotorImpl::new());

    println!("{:?}", motor);
    motor.run();
    println!("{:?}", motor);
    motor.stop();
    println!("{:?}", motor);

    println!("{:?}", specialized_motor);
    specialized_motor.run();
    println!("{:?}", specialized_motor);
    specialized_motor.stop();
    println!("{:?}", specialized_motor);
    specialized_motor.run_fast();
    println!("{:?}", specialized_motor);
    specialized_motor.stop();
    println!("{:?}", specialized_motor);
}