If anything has been introduced into the XML that shouldn't be there, you'll see each successive roundtrip create an output that is a little further away from the original file (guitars.xml).

如果说这个过程向XML 文件中引入了不应该有的什么内容，那就是每次后续的往返创建的输出都和原始文件（guitars.xml）离得更远一点。