void setup() {
  // put your setup code here, to run once:
  for (int i = 0; i < 5; i++){
    pinMode(i, OUTPUT);
  }
}

void waterFlowLight(){
  for (int i = 0; i < 5; i++){
    if (i == 0){
      digitalWrite(0, HIGH);
      digitalWrite(4, LOW);
    }
    else{
      digitalWrite(i, HIGH);
      digitalWrite(i-1, LOW);
    }
    delay(200);
  }
}

void loop() {
  // put your main code here, to run repeatedly:
  waterFlowLight();
}