What else needs to be written in the module when working with dle api?

Question

PHP

Hello. I'm trying to implement my registration in a modal window using dle api. The module now looks like this:

<?php
include ('engine/api/api.class.php');
$email = $_POST['ajaxmail'];
$login = $_POST['ajaxname'];
$password = $_POST['ajaxpass'];
$dle_api->external_register( string $login, string $password, string $email, int 5);
?>

I connected it in index.php with the following line:
require_once ENGINE_DIR . '/modules/mod_reg.php';
Opening mod_reg.php leads to the following error:

Parse error: syntax error, unexpected '$login' (T_VARIABLE) in F:\openserver\OpenServer\domains\mak.eeva\engine\modules\mod_reg.php on line 6

Can you tell me what else needs to be written to get rid of this error?
PS I use dle 11