Arduino mini project-Traffic light

For this mini project, things are simple and straight forward, simply tell the LED when to turn on and off, its a things that I could write the program on my own but I still decided to post it because my final idea has something to do with this sort of layout, and it does give me idea of how am I going to approach it in a better way.

code for this project:

int ledred=10; 
int ledyellow=7; 
int ledgreen=4; 

void setup()
{

 pinMode(ledred,OUTPUT);
 pinMode(ledyellow,OUTPUT);
 pinMode(ledgreen,OUTPUT);

}

void loop() {

digitalWrite(ledred,HIGH);
 delay(1000);
digitalWrite(ledred,LOW);
digitalWrite(ledyellow,HIGH); 
delay(200);
digitalWrite(ledyellow,LOW);
digitalWrite(ledgreen,HIGH);
delay(1000);
digitalWrite(ledgreen,LOW);

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