Good code

// Project - Cycle leds

// Declare

// Led pins
const int RED_LED 	= 2;
const int GREEN_LED = 3;
const int BLUE_LED 	= 4;

// Delay time
const int DELAY_PAUSE = 1000;

// Setup
void setup() {

  // Define pinss
  pinMode(RED_LED, OUTPUT);
  pinMode(GREEN_LED, OUTPUT);
  pinMode(BLUE_LED, OUTPUT);
  
  // Reset pins
  allOff();
}

// Run
void loop() {
  
  // Init state
  allOff();
  
  // Light red
  digitalWrite(RED_LED, HIGH);
  delay(DELAY_PAUSE);
  
  // Light green
  digitalWrite(GREEN_LED, HIGH);
  delay(DELAY_PAUSE);
  
  // Light blue
  digitalWrite(BLUE_LED, HIGH);
  delay(DELAY_PAUSE);
}

// Logic
void allOff(){
  digitalWrite(RED_LED, LOW);
  digitalWrite(GREEN_LED, LOW);
  digitalWrite(BLUE_LED, LOW);
}