返回百分比进程的Php回调

I have a download method from a library that accepts callback function for handling percents of downloaded file.

$cb = function ($percent) {
    echo $percent;
};


$info = $MadelineProto->download_to_dir($messageMediaPhoto, 'assets', $cb);

But it only echos 100 at the end. How can I get the all percents? How can it be done in a blocking io language?

This is fixed in the latest version of MadelineProto.