This is used as a special "fake" template that can be handled by the TemplateList to do pattern matching on nodes.

这个算法是基于动态规划（DP）的思想，解决了发音长短不一的模板匹配问题，简单来说，就是通过构建一个邻接矩阵，寻找最短路径和。-This algorithm is based on the idea of ​ ​ dynamic programming (DP) to solve the problem of template matching pronunciation of varying lengths, in simple terms, is by building a

Summary: interface for the key matching used in key() and template matches. Descr iption: implementation of the key mechanims.