void setup() {
  for(int i=6; i<10; i++)// put your setup code here, to run once:
pinMode(i, OUTPUT);

}

void loop() {
  for(int i=6; i<10; i++)// put your main code here, to run repeatedly:
digitalWrite(i, LOW);
delay(500);
for(int i=6; i<10; i++)
digitalWrite(i, HIGH);
delay(500);
}