// traffic light module

int redLed = 13;
int yellowLed = 12;
int greenLed = 11;
int delayTime = 1000;

void setup() {
  pinMode(redLed, OUTPUT);
  pinMode(yellowLed, OUTPUT);
  pinMode(greenLed, OUTPUT);
}

void loop() {
  // red led
  digitalWrite(redLed, true);
  delay(delayTime);
  digitalWrite(redLed, false);
  delay(delayTime);

  // yellow led
  digitalWrite(yellowLed, true);
  delay(delayTime);
  digitalWrite(yellowLed, false);
  delay(delayTime);

  // green led
  digitalWrite(greenLed, true);
  delay(delayTime);
  digitalWrite(greenLed, false);
  delay(delayTime);
}