int timer = 100;  //delay time for blinking
int ledPin;      // variable to set the ouput pin
void setup()
{
  //loop to initialize the pin mode of digital pins 2 to 7
  ledPin = 2;
  do
  {
    pinMode (ledPin, OUTPUT);
    ++ledPin;
  }while (ledPin < 8); // end loop
} // end of setup()

void loop()
{
  //for loop to blink from pin 2 through to pin 7 with a delay time mentioned in timer
  ledPin = 2;
  do
  {
    digitalWrite (ledPin, HIGH);
    delay (timer);
    digitalWrite (ledPin, LOW);
    ++ledPin;
  }while (ledPin < 8);// end of for loop

  //for loop to blink from pin 7 through to pin 2 with a delay time mentioned in timer
  ledPin = 7;
  do
  {
    digitalWrite (ledPin, HIGH);
    delay (timer);
    digitalWrite (ledPin, LOW);
    --ledPin;
  }while (ledPin >= 2); // end for loop
} // end program