xml entities are not preserved

[msklvsk]

In our team we encode all space characters other than plain space as entities so you can tell one from another. But they aren't preserved by read/serialize. Is it a bug or expected behavior? Is there any way to preserve them?

var libxmljs = require("libxmljs");

var doc = libxmljs.parseXml("<x>&#160;</x>");
console.log(doc.toString());  // outputs '<x> </x>' while original '<x>&#160;</x>' wanted