#define TRUE 1
#define FALSE 2
const int num =4; //number of leds
const int GPIO[] = {0,4,10,14};
const int blink = 100;
static bool flag = TRUE;//flag is not a const as it toggles b/w true and false
void setup() {
for(int led=0;led<num;led++){
  pinMode(GPIO[led], OUTPUT);
}
}

void loop() {
 
  for(int led=0;led<num;led++){
  control(led,flag);
}
  delay(blink);
  flag=!flag; 
}
void control(int led,bool state){
  if(state==TRUE)
  digitalWrite(GPIO[led], HIGH);
  else 
  digitalWrite(GPIO[led], LOW);
}