Semaforo Arduino

void setup () {
 pinMode (2,OUTPUT);
 pinMode (3,OUTPUT);
 pinMode (4,OUTPUT);
}

void loop() {
 digitalWrite(2,HIGH);
 delay(4000);
 digitalWrite(2,LOW);
 delay(2000);
digitalWrite(3,HIGH);
 delay(2000);
 digitalWrite(3,LOW);
 delay(2000);
digitalWrite(4,HIGH);
 delay(4000);
 digitalWrite(4,LOW);
 delay(2000);
 digitalWrite(3,HIGH);
 delay(2000);
 digitalWrite(3,LOW);
 delay(2000);
}