#define LED_PIN 2
#define BUTTON_PIN 13

void setup() {
  pinMode(LED_PIN, OUTPUT);
  pinMode(BUTTON_PIN, INPUT);
}

void loop() {
  if (digitalRead(BUTTON_PIN) == LOW) { // Pushed
    // Blink LED
    digitalWrite(LED_PIN, HIGH);
    delay(200);
    digitalWrite(LED_PIN, LOW);
    delay(200);
  } else { // Not pushed
    // Turn off LED
    digitalWrite(LED_PIN, LOW);
  }
}