/**
  * Bootstrap any application services.
  *
  * @return void
  */
 public function boot()
 {
     \App\Attack::observe(new \App\Observers\AttackObserver());
     \App\Defence::observe(new \App\Observers\DefenceObserver());
     \App\Risk::observe(new \App\Observers\RiskObserver());
     \App\Tree::observe(new \App\Observers\TreeObserver());
     \App\User::observe(new \App\Observers\UserObserver());
 }