int led1 = D3;

void setup()
{
   //Register Particle function 
   Particle.function("led", ledControl);
   pinMode(led1, OUTPUT);
   digitalWrite(led1, LOW);
}

int ledControl(String command)
{
   int state = LOW;

   if(command == "HIGH"){
	   state = HIGH;
   }else if(command == "LOW"){ 
	   state = LOW;
   }else{
	   return -1;
   }

   digitalWrite(led1, state);
   return 1;
}

void loop() {
    
}