void setup() {
  // Initialize digital pin 8 as an output.
  pinMode(13, OUTPUT);
}

// The loop function runs over and over again forever
void loop() {
  // Turn the LED on (HIGH is the voltage level)
  digitalWrite(13, HIGH);
  delay(1000); // Wait for a second

  // Turn the LED off by making the voltage LOW
  digitalWrite(13, LOW);
  delay(1000); // Wait for a second
}