traffic lights

int red = 7;
 int yellow = 4;
 int green = 8;
void setup() {
  // put your setup code here, to run once:
 pinMode(red, OUTPUT);
 pinMode(yellow, OUTPUT);
 pinMode(green, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:

digitalWrite(red, HIGH);
delay(2000);
digitalWrite(red, LOW);
delay(2000);
digitalWrite(yellow, HIGH);
delay(1000);
digitalWrite(yellow, LOW);
delay(1000);
digitalWrite(green, HIGH);
delay(2000);
digitalWrite(green, LOW);
delay(2000);
digitalWrite(yellow, HIGH);
delay(1000);
digitalWrite(yellow, LOW);
delay(1000);
}