class TrafficLight {
  boolean red, yellow, green;

  TrafficLight() {
    this.red = true;
    this.yellow = false;
    this.green = false;
  }

  //new TrafficLight().change() -> void
  // To change the lights in the US fashion for this TrafficLight
  // Note, will modify the booleans red, yellow, and green
  void change() {
    // this.red... this.yellow ... this.green ...
    if (this.red) {
      this.red = false;
      this.trafficLight.redOff();
      this.green = true;
      this.trafficLight.greenOn();
    } else if (this.yellow) {
      this.red = true;
      this.trafficLight.redOn();
      this.yellow = false;
      this.trafficLight.yellowOff();
    } else { // In this case, the green light must be the only one on
      this.green = false;
      this.trafficLight.greenOff();
      this.yellow = true;
      this.trafficLight.yellowOn();
   } 
 }
  //new TrafficLight().changeBritishStyle() -> void
  // To change the lights in the British fashion for this TrafficLight
  // Note, will modify the booleans red, yellow, and green
  void changeBritishStyle() {
    // this.red... this.yellow ... this.green ...
    if (this.red && !this.yellow) {
      this.yellow = true;
    } else if (this.red && this.yellow) {
      this.red = false;
      this.yellow = false;
      this.green = true;
    } else if (this.green && !this.yellow) {
      this.yellow = true;
    } else if (this.green && this.yellow) {
      this.green = false;
    } else { // In this case, the yellow light must be the only one on
      this.red = true;
      this.yellow = false;
    }
  }

      
      

}