Customize TntSearchQuery error : Argument 1 passed ... must be an instance of Grav\Theme\Event

Hello everyone,
I am trying to customize the output of The TNT search plugin. I am following the explanations available on the plugin page:

I have added the following functions in the php file of my theme:

namespace Grav\Theme;

use Grav\Common\Theme;

class NixholTemplate extends Theme
    public static function getSubscribedEvents() {
        return [
            'onTNTSearchQuery' => ['onTNTSearchQuery', 1000],

    public function onTNTSearchQuery(Event $e) {
        $query = $this->grav['uri']->param('q');

        if ($query) {

            $page = $e['page'];
            $query = $e['query'];
            $options = $e['options'];
            $fields = $e['fields'];
            $gtnt = $e['gtnt'];

            $content = $gtnt->getCleanContent($page);
            $title = $page->title();

            $relevant = $gtnt->tnt->snippet($query, $content, $options['snippet']);

            if (strlen($relevant) <= 6) {
                $relevant = substr($content, 0, $options['snippet']);

            $fields->hits[] = [
                'link' => $page->route(),
                'title' =>  $gtnt->tnt->highlight($title, $query, 'em', ['wholeWord' => false]),
                'content' =>  $gtnt->tnt->highlight($relevant, $query, 'em', ['wholeWord' => false]),

But when I test the plugin I am running into this error:
Argument 1 passed to Grav\Theme\NixholTemplate::onTNTSearchQuery() must be an instance of Grav\Theme\Event

Do you know what I am doing wrong? Thanks in advance for your help!

Solved :
Adding these definitions at the beginning of the php file work:

use Grav\Common\Theme;
use RocketTheme\Toolbox\Event\Event;