int yellow = 10;
int red = 11;
int blue = 12;
int green = 13;
int dit = 100;
int dah = 500;

void setup() {
  // put your setup code here, to run once:
pinMode(yellow, OUTPUT);
pinMode(red, OUTPUT);
pinMode(blue, OUTPUT);
pinMode(green, OUTPUT);

}

void loop() {
  // put your main code here, to run repeatedly:
// for pin in (redLED, blueLED, greenLED)
digitalWrite(yellow, HIGH);
delay(dit);
digitalWrite(yellow, LOW);
delay(dah);
digitalWrite(red, HIGH);
delay(dit);
digitalWrite(red, LOW);
delay(dah);
digitalWrite(blue, HIGH);
delay(dit);
digitalWrite(blue, LOW);
delay(dah);
digitalWrite(green, HIGH);
delay(dit);
digitalWrite(green, LOW);
delay(dah);
}