Traffic Lights!!

1int red = 10;
2int yellow = 9;
3int green = 8;
4void setup(){
5    pinMode(red, OUTPUT);
6    pinMode(yellow, OUTPUT);
7    pinMode(green,  OUTPUT);
8}
9void loop(){
10    changeLights();
11    delay(15000);
12}
13void  changeLights(){
14    // green off, yellow on for 3 seconds
15    digitalWrite(green,  LOW);
16    digitalWrite(yellow, HIGH);
17    delay(3000);
18    // turn off  yellow, then turn red on for 5 seconds
19    digitalWrite(yellow, LOW);
20    digitalWrite(red,  HIGH);
21    delay(5000);
22    // red and yellow on for 2 seconds (red is already  on though)
23    digitalWrite(yellow, HIGH);
24    delay(2000);
25    // turn  off red and yellow, then turn on green
26    digitalWrite(yellow, LOW);
27    digitalWrite(red,  LOW);
28    digitalWrite(green, HIGH);
29    delay(3000);
30}