void setup() {
  // put your setup code here, to run once:
  //blink
  pinMode(13, OUTPUT);//set pin 13 as an output
  pinMode(12, OUTPUT);

}

void loop() {
  // put your main code here, to run repeatedly:
  digitalWrite(13, HIGH);
  delay(1000);
  digitalWrite(12, LOW);
  delay(1000);
  digitalWrite(13, LOW);
  delay(1000);
  digitalWrite(12, HIGH);
  delay(1000);
  //this changing of pin number is use to change the blinking of 2 bulbs
  //when 1 buld is blink other is off

}