unsigned char RED_LED = 23;

unsigned char YELLOW_LED = 19;

unsigned char GREEN_LED = 18;

int my_var = 100;

void setup() {
  pinMode(RED_LED, OUTPUT);
  pinMode(YELLOW_LED, OUTPUT);
  pinMode(GREEN_LED, OUTPUT);
  Serial.begin(115200);

  Serial.print("my_var = "); Serial.print(my_var, DEC);
  }

void loop() {

//Serial.print("LEDs On");
 digitalWrite(RED_LED, HIGH);
 digitalWrite(YELLOW_LED, HIGH);
 digitalWrite(GREEN_LED, HIGH);

 delay(2000);

//Serial.print("LEDs Off");
 digitalWrite(RED_LED, LOW);
 digitalWrite(YELLOW_LED, LOW);
 digitalWrite(GREEN_LED, LOW);

 delay(2000);
}