int aOne = 1;
    int aTwo = 2;
    int aThree = 3;
    int bOne = 4;
    int bTwo = 5;
    int bThree = 6;
    int cOne = 7;
    int cTwo = 8;
    int cThree = 9;
    int dOne = 10;
    int dTwo = 11;
    int dThree = 12;
    // LED connected to digital pin 13

    // The setup() method runs once, when the sketch starts

    void setup() {
    // initialize the digital pin as an output:
    pinMode(aOne, OUTPUT);
    pinMode(aTwo, OUTPUT);
    pinMode(aThree, OUTPUT);
    pinMode(bOne, OUTPUT);
    pinMode(bTwo, OUTPUT);
    pinMode(bThree, OUTPUT);
    pinMode(cOne, OUTPUT);
    pinMode(cTwo, OUTPUT);
    pinMode(cThree, OUTPUT);
    pinMode(dOne, OUTPUT);
    pinMode(dTwo, OUTPUT);
    pinMode(dThree, OUTPUT);
    }

    // the loop() method runs over and over again,
    // as long as the Arduino has power

    void loop()
    {
    digitalWrite(aOne, HIGH); // set the LED on
    delay(100); // wait for a second
    digitalWrite(aOne, LOW); // set the LED off
    delay(100); // wait for a second

    digitalWrite(aTwo, HIGH);
    delay(100);
    digitalWrite(aTwo, LOW);
    delay(100);
    digitalWrite(aThree, HIGH);
    delay(100);
    digitalWrite(aThree, LOW);
    delay(100);
    digitalWrite(bOne, HIGH);
    delay(100);
    digitalWrite(bOne, LOW);
    delay(100);
    digitalWrite(bTwo, HIGH);
    delay(100);
    digitalWrite(bTwo, LOW);
    delay(100);
    digitalWrite(bThree, HIGH);
    delay(100);
    digitalWrite(bThree, LOW);
    delay(100);
    digitalWrite(cOne, HIGH);
    delay(100);
    digitalWrite(cOne, LOW);
    delay(100);
    digitalWrite(cTwo, HIGH);
    delay(100);
    digitalWrite(cTwo, LOW);
    delay(100);
    digitalWrite(cThree, HIGH);
    delay(100);
    digitalWrite(cThree, LOW);
    delay(100);
    digitalWrite(dOne, HIGH);
    delay(100);
    digitalWrite(dOne, LOW);
    delay(100);
    digitalWrite(dTwo, HIGH);
    delay(100);
    digitalWrite(dTwo, LOW);
    delay(100);
    digitalWrite(dThree, HIGH);
    delay(100);
    digitalWrite(dThree, LOW);
    delay(100);
    }