// Pin connected to the LED
const int ledPin = 13;
// Setup function runs once at the start
void setup()  {
  // Initialize the digital pin as an output
  pinMode(ledPin, OUTPUT); 
}
// Loop function runs repeatedly
void loop()  {
  // Turn the LED on
  digitalWrite(ledPin, HIGH);
  // Wait for 1 second 
  delay(1000);
  // Turn the LED off 
  digitalWrite(ledPin, LOW);
  // Wait for 1 second
  delay(1000);
}