const byte bule_LED = 4;
 const byte red_LED = 16;
 const byte yel_LED = 17;

#define ON HIGH
#define OFF LOW

const boolean on = true;
const boolean off = false;

void setup() {
  
  pinMode(bule_LED, OUTPUT); // bule LED
  pinMode(red_LED, OUTPUT); // red LED
  pinMode(yel_LED, OUTPUT); // yellow LED
}

void loop() {
  digitalWrite(bule_LED, ON);  // compolier command
  digitalWrite(red_LED, ON);
  digitalWrite(yel_LED, ON);
  delay(300); //milli second (ms)
  digitalWrite(bule_LED, off);
  digitalWrite(red_LED, off);  // boolean variable
  digitalWrite(yel_LED, off);
  delay(700); 
}