int LED=9;             // Sets LED equal to 13
int flash = 500;        // blinking rate

void setup() 
{
    pinMode(LED, OUTPUT);    //Pin 13 controls onboard LED and sets it ready for output 
}

void loop() {
  digitalWrite (LED, HIGH); //Turns on onboard LED

delay(flash);               //Pauses by the value of flash in 1000th of seconds

digitalWrite (LED, LOW);  // Turns off onboard LED

delay(flash);             // Pauses by the value of flash in 1000th of seconds

}