int red = 1;
int green = 2;
int yellow = 3;
int purple = 4;
int del = 80;
void setup(){
  pinMode(red,OUTPUT);
  pinMode(green,OUTPUT);
  pinMode(yellow,OUTPUT);
  pinMode(purple,OUTPUT);
}
void loop(){
  // red
  digitalWrite(red,HIGH);
  delay(del);
  digitalWrite(red,LOW);
  // green
  digitalWrite(green, HIGH);
  delay(del);
  digitalWrite(green, LOW);
  // yellow
  digitalWrite(yellow, HIGH);
  delay(del);
  digitalWrite(yellow, LOW);
  // purple
  digitalWrite(purple, HIGH);
  delay(del);
  digitalWrite(purple, LOW);
}