char led_red = 23;
char led_yellow = 19;
char led_green = 18;

// i have a variable name led_red
//its value is 23

// i have a variable name led_yellow
//its value is 19

// i have a variable name led_green
//its value is 18

void setup() {
  // put your setup code here, to run once:
 pinMode(led_red,OUTPUT);
 pinMode(led_yellow,OUTPUT);
 pinMode(led_green,OUTPUT);

 Serial.begin(9600);
 //9600 bit per second , the data flow spped
 //Serial.println("Testing 1!");


}

void loop() {
  // put your main code here, to run repeatedly:
  Serial.println("On");
  digitalWrite(led_red,HIGH);
  digitalWrite(led_yellow,HIGH);
  digitalWrite(led_green,HIGH);
  delay(200);


  Serial.println("Off");
  digitalWrite(led_red,LOW);
  digitalWrite(led_yellow,LOW);
  digitalWrite(led_green,LOW);
  delay(200);
}