int redLed=12;   // pin for red LED
int yelowLed=8;   // pin for yelow LED
int greenLed=7;  // pin for green LED



void setup() {
  // put your setup code here, to run once:
   pinMode(redLed, OUTPUT);
   pinMode(yelowLed, OUTPUT);
   pinMode(greenLed, OUTPUT);

}

void loop() {
  // red LED on
digitalWrite(redLed, HIGH);
digitalWrite(yelowLed, LOW);
digitalWrite(greenLed, LOW);
delay(2000);// wait 5 seconds

// yelow LED on
digitalWrite(redLed, LOW);
digitalWrite(yelowLed, HIGH);
digitalWrite(greenLed, LOW);
delay(500);// wait 5 seconds


// green LED on
digitalWrite(redLed, LOW);
digitalWrite(yelowLed,LOW);
digitalWrite(greenLed, HIGH);
delay(2000);// wait 5 seconds


}