These functions take a set of inputs and return a set of outputs to accomplish a specific task.

这些函数接受一组输入并返回一组输出，从而完成特定的任务。

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This element allows the programmer to take a set of nodes, group it by some criteria, and then process each group formed by that selection process.

这个元素允许程序员获取一组节点，按某些标准来进行分组，然后处理由那一选择过程组成的每一个组。

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This element allows the programmer to take a set of nodes, group it by some criteria, and then process each group formed by that selection process.

这个元素允许程序员获取一组节点，按某些标准来进行分组，然后处理由那一选择过程组成的每一个组。

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