void setup() {
  // put your setup code here, to run once:
pinMode(13,OUTPUT);
pinMode(12, OUTPUT);
pinMode(11, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
digitalWrite(13,HIGH);

digitalWrite(13,LOW);
digitalWrite(12,HIGH);

digitalWrite(12,LOW);
digitalWrite(11,HIGH);

digitalWrite(11,LOW);
delay(2000);
}