int leds[] = {13, 12, 11, 10, 9};
int currentState[]   = {LOW, LOW, LOW, LOW, LOW};
int currentHighLed = 0;
 
void setup() {
  for   (int i = 0; i < sizeof(leds)/sizeof(int); i=i+1) {
  pinMode(leds[i], OUTPUT);
  //INPUT: to read the tension value on this pin
  //OUTPUT: to regulate the tension value on this pin: e.g. switch on / off
  }
}

void   loop() {
  for (int i = 0; i < sizeof(leds)/sizeof(int); i= i+1) {
  digitalWrite(leds[i], currentState[i]);
  }
  currentState[currentHighLed]   = HIGH;
  delay(700);
  currentHighLed= currentHighLed+1;
  if (currentHighLed > 5) {
    currentHighLed = 0;
    for (int i = 0; i < sizeof(leds)/sizeof(int); i= i+1) {
      currentState[i]   = LOW; 
    }
    delay (1000);
  }
}