public void handleRequest(PlanetEnum request) {
   if(request == PlanetEnum.MERCURY) {
   System.out.println("MercuryHandler handles " + request) ;
   System.out.println("Mercury i s hot .\n") ;
    }
   else{
    System.out.println("MercuryHandler doesn t handle " + request) ;
    if(successor != null) {
    successor.handleRequest(request);
    }
   }
  }