This collection of coercion methods (i.e. as(obj, "type")) allows users of the XML package to switch between different representations of XML nodes and to map from an XML document to the root node and from a node to the document. This helps to manage the nodes
这个集合的强制方法(即as(obj, "type"))允许用户XML包切换不同的表示XML节点之间的映射从一个XML文档的根节点,并从一个节点到文档中。这有助于管理节点