const int numLEDS=4;
const int delayTime=500;
int ledpins[]={6,7,8,9}

void setup() {
  // put your setup code here, to run once:
}
for (int i=0;i<numLEDS;i++){
pinmode(ledpins[i],OUTPUT);
}
void loop() {
  // put your main code here, to run repeatedly:
for (int i=0;i<numLEDS;I++){
  digitalWrite(led pins[i], HIGH);
  delay(delayTime);
  digitalWrite(ledpins[i],LOW);
}
}