(test)arduino, signal lamp(red/yellow/green)

<<CODE>>

int REDpin = 6;

int YELLOWpin = 5;

int GREENpin = 4;

void setup() {

  // put your setup code here, to run once:

  pinMode(REDpin, OUTPUT);

  pinMode(YELLOWpin, OUTPUT);

  pinMode(GREENpin, OUTPUT);

}

void loop() {

  // put your main code here, to run repeatedly:

digitalWrite(REDpin, HIGH);

delay(3000);

digitalWrite(REDpin, LOW);

digitalWrite(YELLOWpin, HIGH);

delay(3000);

digitalWrite(YELLOWpin, LOW);

digitalWrite(GREENpin, HIGH);

delay(3000);

digitalWrite(GREENpin, LOW);

}