// Define the pin number for the LED
const int ledPin = 13;  

void setup() {
  // Initialize the digital pin as an output
  pinMode(ledPin, OUTPUT);  
}

void loop() {
  digitalWrite(ledPin, HIGH);  // Turn the LED on
  delay(2000);                  // Wait for a second
  digitalWrite(ledPin, LOW);   // Turn the LED off
  delay(2000);                  // Wait for a second
}