Can we use PHP classes in our zephir program?

I cannot understand, is it possible to use PHP classes in our zephir program or not? For example:

namespace Myzephir;

class Hello
{
    public static function say()
    {
        Fuel\Core\Log::debug('hello');
        echo "hello\n";
    }
}

How can I include fuel/core/classes/log.php to use Log class? Thank you.

It is not possible