Traffic Light

#define greenLED 7
#define yellowLED 8
#define redLED 9

void setup(){
    Serial.begin(9600);
    pinMode(greenLED, OUTPUT);
    pinMode(yellowLED, OUTPUT);
    pinMode(redLED, OUTPUT);
}

void loop(){
    digitalWrite(redLED, HIGH);
    delay(2000);
    digitalWrite(redLED, LOW);

    digitalWrite(yellowLED, HIGH);
    delay(2000);
    digitalWrite(yellowLED, LOW);

    digitalWrite(greenLED, HIGH);
    delay(2000);
    digitalWrite(greenLED, LOW);
}