int LED=9;
const int BUTTON = 2;
boolean lastButton = LOW;
boolean currentButton = LOW;
boolean ledstatus = LOW;
void setup() {
  // put your setup code here, to run once:
pinMode(LED , OUTPUT);
pinMode(BUTTON , INPUT);
}


boolean debounce(boolean prev)
{
  boolean current = digitalRead(BUTTON);
  if (prev != current)
  {
    delay(5);
    current = digitalRead(BUTTON);
  }
  return current;
}


void loop()
{
  currentButton = debounce(lastButton);
  if (currentButton == HIGH && lastButton == LOW)
  { 
    ledstatus = !ledstatus;
  }
  lastButton = currentButton;

  digitalWrite (LED, ledstatus);
}