int led = LED_BUILTIN; // https://docs.arduino.cc/language-reference/en/variables/constants/ledbuiltin/

void setup() {
  // put your setup code here, to run once:
  pinMode(led, OUTPUT);
  // Initialize Serial Communication
  Serial.begin(9600); // Set the baud rate
  Serial.print("led pin is: ");
  Serial.println(led); // led pin is: 13
}

void loop() {
  // put your main code here, to run repeatedly:
  digitalWrite(led, HIGH);
  delay(2000);
  digitalWrite(led, LOW);
  delay(2000);
}