public function __invoke()
 {
     $input = $this->loadInput("Day18/Puzzle1");
     $controller = new GridController();
     $grid = $controller->startGrid($input);
     for ($i = 1; $i <= 100; $i++) {
         $grid = $controller->nextGrid($grid);
     }
     $this->write("Number of lights after 100 steps: " . $grid->numberTurnedOn());
 }