const byte LED_BUILTIN = 12
void setup() {
  pinMode('LED_BUILTIN', OUTPUT);
  Serial.begin(10000);
}
void loop(){
  digitalRead(LED_BUILTIN,HIGH);
  Serial.println("led on");
  delay(1000);
  digitalWrite(LED_BUILTIN, LOW);
  Serial.println("led off");
  delay(1000);
}