Arduino IDE Coding

int redLED = 9;
int yellowLED = 8;
int greenLED = 7;

void setup() {
  pinMode(redLED, OUTPUT);
  pinMode(yellowLED, OUTPUT);
  pinMode(greenLED, OUTPUT);
}

void loop() {

  // Red Light
  digitalWrite(redLED, HIGH);
  delay(3000);
  digitalWrite(redLED, LOW);

  // Yellow Light
  digitalWrite(yellowLED, HIGH);
  delay(1000);
  digitalWrite(yellowLED, LOW);

  // Green Light
  digitalWrite(greenLED, HIGH);
  delay(3000);
  digitalWrite(greenLED, LOW);
}