static htmlDocPtr parseHtmlDocument(const char * d, const char * b /* base url */) {
	if (!b)
		b = "";
	htmlParserCtxtPtr parser_context = htmlNewParserCtxt();
	htmlDocPtr document = htmlCtxtReadMemory(parser_context, d, strlen(d), b, NULL /* encoding */, HTML_PARSE_NOWARNING | HTML_PARSE_NOERROR  | HTML_PARSE_RECOVER);
	htmlFreeParserCtxt(parser_context);
	return document;
}
static xmlXPathObjectPtr findNodes(htmlDocPtr document, const char * xpath_query) {
	xmlXPathContextPtr xpath_ctx = xmlXPathNewContext(document);
	xmlXPathObjectPtr nodes = xmlXPathEvalExpression(BAD_CAST xpath_query, xpath_ctx);
	xmlXPathFreeContext(xpath_ctx);
	return nodes;
}
typedef void (*node_function_t)(xmlNodePtr node, void * data);
static void eachNode(xmlXPathObjectPtr nodes, node_function_t f, void * data) {
	xmlNodeSetPtr nodeset = nodes->nodesetval;
	int i, size = nodeset->nodeNr;
	for (i = 0; i < size; i++) {
		xmlNodePtr cur;
		cur = (xmlNodePtr)nodeset->nodeTab[i];
		f(cur, data);
	}
}
void printLinkNode(xmlNodePtr node, void * data) {
	if (node->type == XML_ELEMENT_NODE) {
		xmlAttrPtr href = xmlHasProp(node, BAD_CAST "href");
		if (href) {
			printf("-> Link to '%s'\n", xmlGetProp(node, BAD_CAST "href"));
		}
	}
}