const int ledMerah = 10;
const int ledKuning = 9;
const int ledHijau = 8;

void setup() {
  pinMode(ledMerah, OUTPUT);
  pinMode(ledKuning, OUTPUT);
  pinMode(ledHijau, OUTPUT);
}

void loop() {

  digitalWrite(ledMerah, HIGH);
  delay(1000);
  digitalWrite(ledMerah, LOW);

  digitalWrite(ledKuning, HIGH);
  delay(1000);
  digitalWrite(ledKuning, LOW);

  digitalWrite(ledHijau, HIGH);
  delay(1000);
  digitalWrite(ledHijau, LOW);
}