#define merah 2
#define kuning 3
#define hijau 4

void setup() {
pinMode(merah, OUTPUT);
pinMode(kuning, OUTPUT);
pinMode(hijau, OUTPUT);
}

void loop() {
digitalWrite(merah, HIGH);
digitalWrite(kuning, LOW);
digitalWrite(hijau, LOW);
delay(1000);
digitalWrite(merah, LOW);
digitalWrite(kuning, HIGH);
digitalWrite(hijau, LOW);
delay(1000);
digitalWrite(merah, LOW);
digitalWrite(kuning, LOW);
digitalWrite(hijau, HIGH);
delay(1000);
digitalWrite(merah, LOW);
digitalWrite(kuning, HIGH);
digitalWrite(hijau, LOW);
delay(1000);
}