const int merah = 4;
const int kuning = 3;
const int hijau = 2;
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);
}