const int ledPin = 2;
const int buttonPin = 3;
int buttonstate = 0;

void setup() {
pinMode(ledPin, OUTPUT);
pinMode(buttonPin, INPUT);
}
void loop() {
buttonstate = digitalRead(buttonPin);
if (buttonstate == HIGH) {
digitalWrite(ledPin, HIGH);
delay(1);
}  
else {
digitalWrite(ledPin, HIGH);
delay(20);
digitalWrite(ledPin, LOW);
delay(20);
}
}