public function addLeads($labelId, array $leadIds)
    {
        $batch = [];

        foreach ($leadIds as $user) {
            $batch[] = [
                'method' => 'POST',
                'relative_url' => $labelId . '/label',
                'body' => http_build_query(compact('user'))
            ];
        }

        $batch = json_encode($batch);
        
        return giga_facebook_post('', compact('batch'));
    }