struct LED : Service::LightBulb {               // First we create a derived class from the HomeSpan LightBulb Service

  int ledPin;                                       // this variable stores the pin number defined for this LED
  SpanCharacteristic *power;                        // here we create a generic pointer to a SpanCharacteristic named "power" that we will use below

  // Next we define the constructor for DEV_LED.  Note that it takes one argument, ledPin,
  // which specifies the pin to which the LED is attached.
  
  LED(int ledPin) : Service::LightBulb(){

    power=new Characteristic::On();                 // this is where we create the On Characterstic we had previously defined in setup().  Save this in the pointer created above, for use below
    this->ledPin=ledPin;                            // don't forget to store ledPin...
    pinMode(ledPin,OUTPUT);                         // ...and set the mode for ledPin to be an OUTPUT (standard Arduino function)
    
  } // end constructor

  // Finally, we over-ride the default update() method with instructions that actually turn on/off the LED.  Note update() returns type boolean

  boolean update(){            

    digitalWrite(ledPin,power->getNewVal());        // use a standard Arduino function to turn on/off ledPin based on the return of a call to power->getNewVal() (see below for more info)
   
    return(true);                                   // return true to indicate the update was successful (otherwise create code to return false if some reason you could not turn on the LED)
  
  } // update
};