SKETCH YANG PERLU DIKETIK:
const int numLED = 4;
const int pinLED[numLED] = {8,9,10,11};
void setup() {
   for(int i=0; i<4; i++){
   pinMode(pinLED[i], OUTPUT);
   }
}
void loop() {
     for(int i=0; i<4; i++){
     digitalWrite(pinLED[i], HIGH);
     delay(500);
   }
    
    for(int i=0; i<4; i++){
    digitalWrite(pinLED[i], LOW);
    delay(500);
    }
}