Blink 5

const int LED = 13; //LED is in port 13
const int LED_G = 12; //LED green is in port 12
const int LED_Y = 8; //LED yellow is in port 8
const int BUTTON = 7; //BUTTON is in port 7

int val = 0; //state of the button
int old_val = 0; //previous state of button

int state = 0; // 0 = LED off // 1 = LED on
int stage = 0; // 0 = red // 1 = green // 2 = yellow // 3 = all off

void setup(){
  pinMode(LED, OUTPUT); //port 13 is set to output
  pinMode(LED_G, OUTPUT);//port 12 is set to output
  pinMode(LED_Y, OUTPUT);//port 8 is set to output
  pinMode(BUTTON, INPUT); //port 7 is set to input

}

void loop(){
  val = digitalRead(BUTTON); // value of val is the state of button

  //check if a transition has happened
  //if there was, 
  if ((val == HIGH) && (old_val == LOW)){
    state = 1 - state;
  }

  if ((val ==LOW) && (old_val == HIGH)){
    delay(10);
  }

  if ((val == HIGH) && (state == 1)){
    digitalWrite(LED_G, HIGH);
  }
  
  old_val = val; //set most recent val to old_val

  if (state ==1){
    digitalWrite(LED, HIGH); //turn port 13 to high
    stage = 1;
  }else{
    digitalWrite(LED, LOW); //if state is not 1, port 13 to low
  }
}