Function print value but not return - php

Question

I am trying to configure the Binary.com API, but with some difficulties.
I need to get the message back, but that's not the right way.
In function, if I ask to return the array, it does not return. But if I send a print, the result is displayed on the screen.
See:
require __DIR__ . '/vendor/autoload.php';
$loop = \React\EventLoop\Factory::create();
$connector = new \Ratchet\Client\Connector($loop);
$GLOBALS['app_id'] = XXX;
class Bot {
public static function authorize($loop, $connector, $token, $ret = null) {
if (!is_array($ret)) {
$connector('wss://ws.binaryws.com/websockets/v3?app_id=' . $GLOBALS['app_id'])->then(function ($conn) use ($loop, $token) {
$conn->send("{\"authorize\": \"" . $token . "\"}");
$conn->on('message', function (\Ratchet\RFC6455\Messaging\MessageInterface $msg) use ($conn) {
$conn->close();
Bot::authorize(null, null, json_decode($msg, true));
});
}, function ($e) {
Bot::authorize(null, null, $e->getMessage());
$loop->stop();
});
$loop->run();
}
print_r($ret); //Data is displayed on screen
return $ret;
}
}
$bot = Bot::authorize($loop, $connector, 'a1-tokenxxx');
print_r($bot); //Data is not displayed on screen
See the comments.
Why is this happening?
What is the correct way to return promise data?