public static function get_library($name) {
	if (class_exists('\\alsvanzelf\\fem\\'.$name) == false) {
		throw new exception('library does not exist in fem');
	}
	
	if (isset(self::$custom_libraries[$name])) {
		return self::$custom_libraries[$name];
	}
	
	return '\\alsvanzelf\\fem\\'.$name;
}