void setup() {
  pinMode(25, OUTPUT);
  pinMode(26, OUTPUT);
  pinMode(27, OUTPUT);
}

void loop() { 
  RGB(1,0,0);
  delay(500);
  RGB(0,1,0);
  delay(500);
  RGB(0,0,1);
  delay(500);
}

void RGB(bool red, bool green, bool blue) {
  digitalWrite(25, red);
  digitalWrite(26, green);
  digitalWrite(27, blue);
}