public static void main (string[] args) {
	var document = new GXml.GHtmlDocument.from_uri ("http://www.france24.com/fr/20171021-chine-charbon-centrale-etranger-energie-environnement-leader-climat", GXml.GHtmlDocument.default_options);
	var collection = document.get_elements_by_property_value ("property", "article:published_time");
	/*
	 sometimes current collection contains each element with "property" attribute, sometimes no 
	 */
}
