int ledPin1 = 12, ledPin2 = 4; //defining led pin variables
int delayTime = 900;

void setup() {
  pinMode(ledPin1, OUTPUT); // setting both pins as outputs
  pinMode(ledPin2, OUTPUT);

}

void loop() {
  digitalWrite(ledPin1, HIGH); // blinking led 1
  delay(delayTime);
  digitalWrite(ledPin1, LOW);
  delay(delayTime);
  digitalWrite(ledPin2, HIGH); // blinking led 2
  delay(delayTime);
  digitalWrite(ledPin2, LOW);
  delay(delayTime);
  

}