void setup() { pinMode(7, OUTPUT); }

void flashLED(int time, int iterations, int postdelay, int port) { // Flash an LED
  for (int i=0; i<iterations*2; i++) {        // Flash 3 times (requiring 6 iterations, 1 for on, 1 for off)
    digitalWrite(port, i % 2 == 0 ? HIGH : LOW); // On every EVEN iteration, make HIGH, else make LOW
    delay(time); 
  } 
  delay(postdelay); // Delay at the end of each iteration to avoid very short delays
}

void loop() {
  const int ENDDELAY = 300; // Delay at the end of each letter to avoid very short delays
  flashLED(500, 3, ENDDELAY, 7); // S
  flashLED(200, 3, ENDDELAY, 7); // O
  flashLED(500, 3, ENDDELAY, 7); // S
}