void setup() {
  for (int pin = 2; pin <= 13; pin++) {
    pinMode(pin, OUTPUT); // Define pins 2-13 as output pins
  }
}

void loop() {
  for (int pin = 2; pin <= 13; pin++) {
    digitalWrite(pin, HIGH); // Turning ON the current Pin
    delay(200);              // Wait 0.2 seconds
  }
  for (int pin = 2; pin <= 13; pin++) {
    delay(200);              // Wait 0.2 seconds
    digitalWrite(pin, LOW);  // Turning OFF the current Pin
  }
}