//Global variable

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(13, OUTPUT);
  pinMode(12, OUTPUT);
  pinMode(2, OUTPUT);
}

void loop() {
  // red
  digitalWrite(13, HIGH);
  Serial.println("RED ON");
  delay(50); // this speeds up the simulation
  digitalWrite(13, LOW);
  delay(50);
 
 // yellow
  digitalWrite(12, HIGH);
  Serial.println("YELLOW ON");
  delay(50); // this speeds up the simulation
  digitalWrite(12, LOW);
  delay(50);

// green
  digitalWrite(2, HIGH);
  Serial.println("GREEN ON");
  delay(50); // this speeds up the simulation
  digitalWrite(2, LOW);
  delay(50);
}