int red_led = 2;
int green_led = 3;
int blue_led = 4;

void setup() {
  pinMode(red_led, OUTPUT);
  pinMode(green_led, OUTPUT);
  pinMode(blue_led, OUTPUT);
}

void loop() {
  led_color(0, 255, 255); 
  delay(100);
  led_color(255,0, 255);
  delay(100);
  led_color(255, 255, 0);
  delay(100);
}

void led_color(int red_value, int green_value, int blue_value) { 
  analogWrite(red_led, red_value);
  analogWrite(green_led, green_value);
  analogWrite(blue_led, blue_value);
}