void setup() {
 for(int LED = 2; LED<= 9; LED++) {
  pinMode(LED, OUTPUT);
}
}

void loop() {
 for(int LED = 2; LED<= 9; LED++) {
digitalWrite(LED, HIGH);
delay(50);
digitalWrite(LED, LOW);
 } 

 for(int LED= 2; LED<= 9; LED++) {
digitalWrite(LED, LOW);
delay(20);
 }

 for(int LED= 9; LED>= 2; LED--) {
digitalWrite(LED, HIGH);
delay(50);
digitalWrite(LED, LOW);
 }

 for(int LED= 2; LED<= 9; LED++) {
digitalWrite(LED, LOW);
delay(20);

 }
}