void setup () {
// initialize digital pin LED_BUILTIN as an output.
pinMode (2, OUTPUT);
}
// the loop fuction runs over and over again forever v
void loop () {
digitalWrite(2, HIGH);  // turn the LED on (HIGH is the voltage level)
delay(100);                      // wait for a secund
digitalWrite(2, LOW);   // turn the LED off by marking the voltage LOW
delay(100);                      // wait for a secund 
}