本内容遵循CC 4.0 BY-SA版权协议 domain（领域层） 承载领域核心模型与业务规则，不依赖任何外部框架，是系统最稳定的内核。 model_entity.py、value_object.py application（应用层） 负责业务流程编排与用例驱动，协调领域模型、基础设施与接口层完成具体业务场景。

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As TPG's cruise team lead, Gene Sloan oversees the site's cruise content and also writes many of TPG's main cruise guides. He has spent nearly 30 years writing about cruise ships and cruising, and he ...