int red=2;
int yellow=3;
int green=4;
void setup() {
  pinMode(2,OUTPUT);
  pinMode(3,OUTPUT);
  pinMode(4,OUTPUT);
  Serial.begin(9600);
}

void loop() {
digitalWrite(red,HIGH);
Serial.println("red");
delay(2000);
digitalWrite(red,LOW);
digitalWrite(yellow,HIGH);
Serial.println("yellow");
delay(1000);
digitalWrite(yellow,LOW);
digitalWrite(green,HIGH);
Serial.println("green");
delay(2000);
digitalWrite(green,LOW);
Serial.println("Loop finished");
}