By default, all parent and ancestor nodes above the current context node are displayed.
默认情况下,会显示当前上下文节点上面的所有父节点和祖先节点。
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Methods for determining the ancestor nodes priority number of the expanded node and selecting effectively the ancestor nodes by means of the priority number are also given.
This method tells you all information you need to know: whether one node is descendant of an ancestor of the other, whether it is before or after, and so on.