void setup() {
  pinMode(7, INPUT_PULLUP);
  pinMode(13, OUTPUT);
}

bool led = HIGH ;
void loop() {
  bool sw7  = digitalRead(7);
  if (sw7 == 0) {
    digitalWrite(13, led);
    if (led == HIGH) {
      led = LOW ;
    }
    else {
      led = HIGH ;
    }
    delay(500);
  }
}