#define LED_PIN_RED 7
#define LED_PIN_YELLOW 8
#define LED_PIN_GREEN 12
#define DELAY_TIME 1000

void setup() {
  // put your setup code here, to run once:
  pinMode(LED_PIN_RED, OUTPUT);
  pinMode(LED_PIN_YELLOW, OUTPUT);
  pinMode(LED_PIN_GREEN, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
digitalWrite(LED_PIN_RED, HIGH);
digitalWrite(LED_PIN_YELLOW, LOW);
digitalWrite(LED_PIN_GREEN, LOW);
delay(DELAY_TIME);
digitalWrite(LED_PIN_RED, LOW);
digitalWrite(LED_PIN_YELLOW, HIGH);
digitalWrite(LED_PIN_GREEN, LOW);
delay(DELAY_TIME);
digitalWrite(LED_PIN_RED, LOW);
digitalWrite(LED_PIN_YELLOW, LOW);
digitalWrite(LED_PIN_GREEN, HIGH);
delay(DELAY_TIME);
}