public static function mul(Vector $vector, $value) : Vector {
        $type = get_class($vector);
        $out  = new $type();

        $count = count($out);
        if ($value instanceof Vector === false) {
            $value = new $type(...array_fill(0, $count , $value));
        }

        for ($i=$count;$i-->0;) {
            $out[$i] = $vector[$i] * $value[$i];
        }

        return $out;
    }