void setup() {
  // put your setup code here, to run once:
Serial.begin(115200);
if(!Serial) Serial.println("serial is not ok");
pinMode(3, OUTPUT);
pinMode(4, OUTPUT);
pinMode(5, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
digitalWrite(3, HIGH);
Serial.println("red is on");
delay(3000);
digitalWrite(3, LOW);
Serial.println("red is off");
digitalWrite(4, HIGH);
Serial.println("yellow is on");
delay(3000);
digitalWrite(4, LOW);
Serial.println("yellow is off");
digitalWrite(5, HIGH);
Serial.println("limegreen is on");
delay(3000);
digitalWrite(5, LOW);
Serial.println("limegreen is off");
}