void setup (){
pinMode(8, OUTPUT);
pinMode(9, OUTPUT);
pinMode(10, OUTPUT);

 digitalWrite(8, HIGH);
 digitalWrite(9, HIGH);
 digitalWrite(10, HIGH);
}

void loop(){
  digitalWrite(8,LOW);
  delay(1000);
  digitalWrite(8, HIGH);
  digitalWrite(9, LOW);
  delay(1000);
  digitalWrite(9, HIGH);
  digitalWrite(10,LOW);
  delay(1000);
  digitalWrite(10,HIGH);
}