// the external LED is attached to this pin.
    // onboard LED is attached to pin 13, 
    int ledPin = 13;

    // slider of potentiometer attached to this analog input 
    int analogInPin = 0;

    // length of a dot
    int dotTime = 300;

    // even though we are not using it yet, make sure the
    // pushbutton is set up correctly

    // the pushbutton is attached to this digital input pin
    int buttonPin = 9;
     
    // the value read from the pushbutton
    int buttonValue;

    void setup() {
      // configure ledPin to be a digital output
      pinMode(ledPin, OUTPUT);

      // set buttonPin to INPUT and 
      // turn on internal pull up resistor 
      pinMode(buttonPin, INPUT);
      digitalWrite(buttonPin, HIGH);
    }
     
    void loop() {

      // send out an O: - - -

      // dash 1
      // a dash is 3 dots long
      digitalWrite(ledPin, HIGH);
      delay(3 * dotTime);

      // an inter-element gap is one dot
      digitalWrite(ledPin, LOW);
      delay(dotTime);

      // dash 2
      digitalWrite(ledPin, HIGH);
      delay(3 * dotTime);
      digitalWrite(ledPin, LOW);
      delay(dotTime);

      // dash 3
      digitalWrite(ledPin, HIGH);
      delay(3 * dotTime);
      digitalWrite(ledPin, LOW);
      delay(dotTime);

      // and a short gap between O and the next character
      delay(2 * dotTime);

    }