#define LED_BUILTIN 2// the setup function runs once when you press reset or power the boardvoidsetup(){// initialize digital pin LED_BUILTIN as an output.pinMode(LED_BUILTIN,OUTPUT);}// the loop function runs over and over again forevervoidloop(){digitalWrite(LED_BUILTIN,HIGH);// turn the LED on (HIGH is the voltage level)delay(1000);// wait for a seconddigitalWrite(LED_BUILTIN,LOW);// turn the LED off by making the voltage LOWdelay(1000);// wait for a second}