public static function mapMethod (array $sequence, $method, array $arguments = array())
    {
        if (empty($arguments)) {
            $f = function ($element) use ($method) {
                return $element->$method();
            };
        } else {
            $f = function ($element) use ($method, $arguments) {
                return call_user_func_array(array($element, $method), $arguments);
            };
        }
        return array_map($f, $sequence);
    }