public function handle(SignupCommand $command)
 {
     $userId = UserId::fromString($command->id());
     if ($this->userRepository->has($userId)) {
         return;
     }
     $user = User::signup($userId);
     $this->userRepository->save($user);
 }
 public function handle(RewardUserCommand $command)
 {
     $user = $this->userRepository->byId(UserId::fromString($command->userId()));
     $user->earnPoints($command->points());
     $this->userRepository->save($user);
 }