int led_merah = 1;
int led_kuning = 2;
int led_hijau = 3;

void setup() {
  // put your setup code here, to run once:
pinMode(led_merah, OUTPUT);
pinMode(led_kuning, OUTPUT);
pinMode(led_hijau, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
digitalWrite(led_merah, HIGH);
delay(500);
digitalWrite(led_merah, LOW);
delay(500);
digitalWrite(led_kuning, HIGH);
delay(500);
digitalWrite(led_kuning, LOW);
delay(500);
digitalWrite(led_hijau, HIGH);
delay(500);
digitalWrite(led_hijau, LOW);
delay(500);
}