int i; //Initialise i as an intiger variable
void setup() {
  // Declares pin 13 to 4 as Ouputs 
  pinMode(13,OUTPUT);
  pinMode(12,OUTPUT);
  pinMode(11,OUTPUT);
  pinMode(10,OUTPUT);
  pinMode(9,OUTPUT);
  pinMode(8,OUTPUT);
  pinMode(7,OUTPUT);
  pinMode(6,OUTPUT);
  pinMode(5,OUTPUT);
  pinMode(4, OUTPUT);

}

void loop() {
   // A for loop that switches on the LED lights from pin 13 to pin 4(left to right)
  for(i = 13; i>=4 ; i--){  
  digitalWrite(i,HIGH);
  delay(250);
  digitalWrite(i,LOW);
  }
   // A for loop that switches on the LED lights from pin 13 to pin 4(left to right)
  for(int i = 4 ; i <=13; i++){//A For loop that switches on the LED lights from right to left 
  digitalWrite(i, HIGH);
  delay(250);
  digitalWrite(i, LOW);
  }

}