这两个函数均按照深度优先的顺序遍历树，但两者的差异在于先访问一个节点还是先访问其子节点。

Both functions walk the tree in depth-first order but they differ in whether a node is visited before or after its children.

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FETCH() 函数从主散列或辅散列检索键，这里优先检索主散列。

The FETCH() function retrieves a key from either the primary or the secondary hash, where the primary hash is given preference.

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这些函数允许创建正常、批处理或实时任务（先入，先出 [FIFO] 或循环），具有特定的优先级或高等级。

These functions permit the creation of normal, batch, or real-time tasks (first in, first out [FIFO] or round-robin), with a specific priority or nice level.

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Now downside of this, well, I've just now violated my preference for having main up top, maybe that's forgivable.

现在在后面，我违反了把main函数放在上面的优先级,可能那是可以宽恕的。

哈佛公开课 - 计算机科学课程节选