// variables

int RED   = 11;

int BLUE  = 12;

int BROWN  = 13;

int DELAY_RED = 1000;

int DELAY_BLUE = 500;

int DELAY_BROWN = 2000;

// basic functions

void setup()

{

  pinMode(RED , OUTPUT);

    pinMode(BLUE , OUTPUT);

      pinMode(BROWN , OUTPUT);

      }

      void loop()

      {

        green_light();

          delay(DELAY_RED);

            yellow_light();

              delay(DELAY_BLUE);

                red_light();

                  delay(DELAY_BROWN);

                  }

                  void green_light()

                  {

                    digitalWrite(RED , HIGH);

                      digitalWrite(BLUE , LOW);

                        digitalWrite(BROWN , LOW);

                        }

                        void yellow_light()

                        {

                          digitalWrite(RED , LOW);

                            digitalWrite(BLUE , HIGH);

                              digitalWrite(BROWN , LOW);

                              }

                              void red_light()

                              {

                                digitalWrite(RED , LOW);

                                  digitalWrite(BLUE , LOW);

                                    digitalWrite(BROWN , HIGH);

                                    }