int ledBiru = 2;
  int ledHijau = 5;
  int ledKuning = 7;

void setup() {

  pinMode(ledBiru, OUTPUT);
  pinMode(ledHijau, OUTPUT);
  pinMode(ledKuning, OUTPUT);
}

void loop() {

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

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

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

}