const GLib =;

let markupParser = new GLib.MarkupParser();

Any of the fields in GLib.MarkupParser can be null, in which case they will be ignored. Except for the @error function, any of these callbacks can set an error; in particular the GLib.MarkupError.unknown_element, GLib.MarkupError.unknown_attribute, and GLib.MarkupError.invalid_content errors are intended to be set from these callbacks. If you set an error from a callback, GLib.MarkupParseContext.prototype.parse will report that error back to its caller.