const int lowestPin = 2;
const int highestPin = 9;

void setup() 
{
  for (int thisPin = lowestPin; thisPin <= highestPin; thisPin++)
{
  pinMode (thisPin, OUTPUT);
}
}

void loop() 
{
 for (int thisPin = lowestPin; thisPin <= highestPin; thisPin++);
 {
  digitalWrite(lowestPin, 0);
  delay(100);
 }
 for (int thisPin = highestPin; thisPin >= lowestPin; thisPin--)
 {
  digitalWrite(thisPin, 1);
  delay(100);
 }
 for (int thisPin = highestPin; thisPin >= lowestPin; thisPin--)
 {
  digitalWrite(thisPin, 0);
  delay(100);
 }
 for (int thisPin = lowestPin; thisPin <= highestPin; thisPin++);
 {
  digitalWrite(highestPin, 0);
  delay(100);
 }
}