int lampumerah = 8;
int lampukuning = 9;
int lampuhijau = 10;
void setup() {
  // put your setup code here, to run once:
pinMode(lampumerah, OUTPUT);
pinMode(lampukuning, OUTPUT);
pinMode(lampuhijau, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
digitalWrite(lampumerah, HIGH);
digitalWrite(lampukuning, LOW);
digitalWrite(lampuhijau, LOW);
delay(2000);
digitalWrite(lampumerah, LOW);
digitalWrite(lampukuning, HIGH);
digitalWrite(lampuhijau, LOW);
delay(2000);
digitalWrite(lampumerah, LOW);
digitalWrite(lampukuning, LOW);
digitalWrite(lampuhijau, HIGH);
delay(2000);
}