ia
const int buttonPin = 2;
const int ledpin = 21;
int buttonState 0;
void setup() {
    pinMode(ledPin,OUTPUT);
    pinMode(buttonPin, INPUT_PULLUP);
}
void loop()
   buttonState = digitalRead(buttonPi);
   if (buttonState == HIG) {
       digitalWrite(ledPin, LOW);
   } else {
       digitalWrite(ledPin, HIGH);
   }
}