过滤器还指定达到对照节点所必要的兄弟节点的数量。

The filter also specifies the number of siblings necessary to reach the comparison node.

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如果不满足这些先决条件，则代码将检查新节点的父节点和它的兄弟节点是否都是红节点。

If not, the code checks whether the new node's parent and uncle are both red nodes.

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位置号是必需的，以防节点有相同类型和名称的兄弟节点，这样可以表明我们引用的是哪个节点。

That position number is needed in case the node has siblings of the same type and name, to indicate which one we're referring to.

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