给定一个订单，返回该订单和带产品的行式项目。
Given an order, return it and the line items with product. This delegates to.
给定一个行式项目，返回该行式项目和产品，这将委托给。
Given a line item, return it and the product, which delegates to.
所需时间仅为几分钟或一小时的任务可能需要集中到更大的行式项目中。
Tasks that are only a few minutes or an hour might need to aggrated into a bigger line item.
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