int red = 1;
int yellow = 2;
int green = 3;
int lamp_count = 4;

//keep track on current lamps set
int pos = 0;

void setup() {
  //turn on all red light
  while (pos  < lamp_count) {
    digitalWrite(red + (pos * 3), 1);
    pos += 1;
  }
}

//declaring a new func to control a set of lamps
int lamp(int a, int b, int c, int ms) {
  digitalWrite(red + (pos * 3), a);
  digitalWrite(yellow + (pos * 3), b);
  digitalWrite(green + (pos * 3), c);
  delay(ms);
}

//animate the lamps
int blink(int rep, int ms) {
  int count = 0;

  lamp(0, 1, 0, ms / 2);
  lamp(0, 0, 1, ms);

  //yellow light blinking
  while (count < rep) {
    lamp(0, 1, 0, ms / (rep * 2));
    lamp(0, 0, 0, ms / (rep * 2));
    count += 1;
  }
  lamp(1, 0, 0, ms / 2);
}

void loop() {
  while (pos < lamp_count) {
    //applying the animation into all set of lamps
    blink(5, 2000);

    //change the pin to the next lamps set
    pinMode(red + (pos * 3), OUTPUT);
    pinMode(yellow + (pos * 3), OUTPUT);
    pinMode(green + (pos * 3), OUTPUT); 
    pos += 1;
  }
  pos = 0;
}