int signal1[] = {23,21};
int signal2[] = {19,5};
int signal3[] = {17,4};
void setup(){
 for (int i = 0; i < 2; i++) {
    pinMode(signal1[i], OUTPUT);
    pinMode(signal2[i], OUTPUT);
    pinMode(signal3[i], OUTPUT);
    }  }
void loop(){
  int redDelay= 2000;
  digitalWrite(signal1[1], HIGH);
  digitalWrite(signal2[0], HIGH);
  digitalWrite(signal3[0], HIGH);
   digitalWrite(signal1[0], LOW);
   digitalWrite(signal3[1], LOW);
  delay(redDelay);
  digitalWrite(signal1[1], LOW);
  digitalWrite(signal2[0], LOW);
  digitalWrite(signal3[0], LOW);
  digitalWrite(signal1[0], HIGH);
  digitalWrite(signal3[0], HIGH);
  digitalWrite(signal2[1], HIGH);
  delay(redDelay);
  digitalWrite(signal3[1], HIGH);
  digitalWrite(signal1[0], HIGH);
  digitalWrite(signal2[0], HIGH);
  digitalWrite(signal3[0], LOW);
  digitalWrite(signal2[1], LOW);
  digitalWrite(signal2[1], LOW);
  delay(redDelay);
}