void setup ()
  {
      for (int pin = 2; pin <= 7; pin++)
            {
                       pinMode(pin,
                  OUTPUT);
            }
  }
void semaforo_1()
  {
            digitalWrite(2, HIGH);
            delay(500);
            digitalWrite(2, LOW);
            delay(500);
            digitalWrite(2, HIGH);
            delay(500);
            digitalWrite(2, LOW);
            delay(500);
            digitalWrite(2, HIGH);
            delay(500);
            digitalWrite(2, LOW);
            delay(500);
            digitalWrite(3, HIGH);
            delay(3000);
            digitalWrite(3, LOW);
            digitalWrite(4, HIGH);
            digitalWrite(7, LOW);
            semaforo_2();
   }
void semaforo_2()
  {
            digitalWrite(5, HIGH);
            delay(500);
            digitalWrite(5, LOW);
            delay(500);
            digitalWrite(5, HIGH);
            delay(500);
            digitalWrite(5, LOW);
            delay(500);
            digitalWrite(5, HIGH);
            delay(500);
            digitalWrite(5, LOW);
            delay(500);
            digitalWrite(6, HIGH);
            delay(3000);
            digitalWrite(6, LOW);
            digitalWrite(7, HIGH);
            digitalWrite(4, LOW);
            semaforo_1();
  }
void loop()
  {
       for (int pin = 2;
                  pin <= 7; pin++)
                   {
                        digitalWrite(pin, LOW);
                   }
            digitalWrite(2, HIGH);
            digitalWrite(7, HIGH);
            semaforo_1();
  }