int RedLED = 12;
int YellowLED = 10;
int GreenLED = 8;
void setup() {
  // put your setup code here, to run once:
  pinMode(RedLED,OUTPUT);
  pinMode(YellowLED,OUTPUT);
  pinMode(GreenLED,OUTPUT);

  digitalWrite(RedLED,LOW);
  digitalWrite(YellowLED,LOW);
  digitalWrite(GreenLED,LOW);

  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
// Yield Mode
  digitalWrite(RedLED,LOW);
  digitalWrite(YellowLED,HIGH);
  digitalWrite(GreenLED,LOW);
  Serial.println("Light Mode: Yield ");
  delay(1000);

// Go Mode
  digitalWrite(RedLED,LOW);
  digitalWrite(YellowLED,LOW);
  digitalWrite(GreenLED,HIGH);
  Serial.println("Light Mode: Go ");
  delay(2000);

// Stop Mode
  digitalWrite(RedLED,HIGH);
  digitalWrite(YellowLED,LOW);
  digitalWrite(GreenLED,LOW);
  Serial.println("Light Mode: Stop ");
  delay(2000);
}