void setup(){
pinMode(12, OUTPUT);
pinMode(10, OUTPUT); 
pinMode(8, OUTPUT);
}
void loop() {
 digitalWrite(12, HIGH);
 delay(1000);
 digitalWrite(12, LOW);
 digitalWrite(10, HIGH);
 delay(1000);
 digitalWrite(10, LOW);
 digitalWrite(8, HIGH);
 delay(1000);
 digitalWrite(8, LOW);
 digitalWrite(10, HIGH);
 delay(1000);
 digitalWrite(10, LOW);
}