code: public function execute($command, callable $next)
      {
          if (null === $this->handlers) {
              return $next($command);
          }
  
          if (!($command instanceof CommandInterface)) {
              return $next($command);
          }
  
          $handlers = array_filter($this->handlers, function (CommandHandlerInterface $handler) use ($command) {
              return $handler->supports($command);
          });
  
          if (0 === count($handlers)) {
              throw NotFoundException::fromCommand($command);
          }
  
          foreach ($handlers as $handler) {
              $handler->handle($command);
          }
  
          return $next($command);
      }
docs: {@inheritdoc}