const int RED_LED_PIN = 12;
const int GREEN_LED_PIN = 10;
const int BLUE_LED_PIN = 8;

void setup() {
  pinMode(RED_LED_PIN, OUTPUT);
  pinMode(GREEN_LED_PIN, OUTPUT);
  pinMode(BLUE_LED_PIN, OUTPUT);
}

void loop() {
  setLeds(true, false, false);
  delay(500);
  setLeds(false, true, false);
  delay(500);
  setLeds(false, false, true);
  delay(500);
}

void setLeds(bool red, bool green, bool blue) {
  digitalWrite(RED_LED_PIN, red);
  digitalWrite(GREEN_LED_PIN, green);
  digitalWrite(BLUE_LED_PIN, blue);
}