void setup()
{
  // define pin modes
   pinMode(2,OUTPUT); //pin6-a led
   pinMode(3,OUTPUT); //pin7-b led
   pinMode(4,OUTPUT); //pin8-c led
   pinMode(5,OUTPUT); //pin9-d led
   pinMode(6,OUTPUT); //pin10-e led
   pinMode(7,OUTPUT); //pin11-f led
   pinMode(8,OUTPUT); //pin12-g led
 }
 void loop() 
{
  // loop to turn leds of seven seg ON  
  for(int i=2;i<9;i++)     //for_loop-1
  {
    digitalWrite(i, LOW); //digitalWrite(6-12,LOW);
    delay(500);	//500ms
  } 
  //delay(1000);    //1sec delay
  // loop to turn leds of seven seg OFF
  for(int i=2;i<9;i++)      //for_loop-2
  {
    digitalWrite(i, HIGH); //digitalWrite(6-12,HIGH);
    delay(500);	//0.5 seconds
  }
   delay(1000);    //1sec delay
}