const int lowestPin = 2;
const int highestPin = 9;
void setup() {
  // put your setup code here, to run once:
  for (int thisPin = lowestPin; thisPin <= highestPin; thisPin++) {
    pinMode(thisPin, OUTPUT);
  }
}
void led_Right_to_Left(){
   for (int thisPin = lowestPin; thisPin <= highestPin; thisPin++) {
    digitalWrite(thisPin, 1);
    delay(200);
  }

  for (int thisPin = highestPin; thisPin >= lowestPin; thisPin--) {
    digitalWrite(thisPin, 0);
    delay(200);
  }
  
}
void led_Left_to_Right(){

  for (int thisPin = highestPin; thisPin >= lowestPin; thisPin--) {
    digitalWrite(thisPin, 1);
    delay(200);
  }

  for (int thisPin = lowestPin; thisPin <= highestPin; thisPin++) {
    digitalWrite(thisPin, 0);
    delay(200);
  }
}
void loop() {
  // put your main code here, to run repeatedly:
 led_Right_to_Left();
 led_Left_to_Right();
  
  
}