void setup() {
  pinMode(13, OUTPUT); // Red LED
  pinMode(12, OUTPUT); // Green LED
  pinMode(11, OUTPUT); // Blue LED
}

void loop() {
  digitalWrite(13, HIGH); // Turn on Red LED
  delay(500); // Wait for 500 milliseconds
  digitalWrite(13, LOW); // Turn off Red LED
  digitalWrite(12, HIGH); // Turn on Green LED
  delay(500); // Wait for 500 milliseconds
  digitalWrite(12, LOW); // Turn off Green LED
  digitalWrite(11, HIGH); // Turn on Blue LED
  delay(500); // Wait for 500 milliseconds
  digitalWrite(11, LOW); // Turn off Blue LED
}