public ArticleAggregateRoot()
{
RegisterApply<ArticleCreatedEvent>(Apply);
RegisterApply<ArticleUnavailableEvent>(Apply);
RegisterApply<ArticleAvailableEvent>(Apply);
RegisterHandler<CreateArticleCommand>(Handle);
RegisterHandler<MakeArticleUnavailableCommand>(Handle);
RegisterHandler<MakeArticleAvailableCommand>(Handle);
RegisterHandler<SellArticleCommand>(Handle);
}