const int Red_Light =25;
const int Yellow_Light =26;
const int Green_Light =27;
const long Waktu_Brenti = 20000;
const long Waktu_Beralih = 3000; 

void setup() {
  // put your setup code here, to run once:
  pinMode(Red_Light, OUTPUT);
  pinMode(Yellow_Light, OUTPUT);
  pinMode(Green_Light, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  digitalWrite(Red_Light, HIGH);
  digitalWrite(Yellow_Light, LOW);
  digitalWrite(Green_Light, LOW);
  delay(Waktu_Brenti); // this speeds up the simulation
  digitalWrite(Red_Light, LOW);
  digitalWrite(Yellow_Light, HIGH);
  digitalWrite(Green_Light, LOW);
  delay(Waktu_Beralih); // this speeds up the simulation
  digitalWrite(Red_Light, LOW);
  digitalWrite(Yellow_Light, LOW);
  digitalWrite(Green_Light, HIGH);
  delay(Waktu_Brenti); // this speeds up the simulation
}