function send($registration_ids, $message) {
        $fields = array(
            'registration_ids' => $registration_ids,
            'data' => $message,
        ); 
        // stop($fields);
        return sendPushNotification($fields);
    }

    function sendPushNotification($fields) { 
        define('FIREBASE_API_KEY', 'AAAA9HYH3yg:APA91bFdlyT3aZc7I48rKHT8bHph3p1tDyoDfoLeAwqdO_CeKwIQa55_VdOiILRvEs4A7XOhaRTBnweI6NkwEjoL68-3o1Yexk2dXjrXj4BfulU39ZeFA-mgjdgbz3jLCKe4038EBjSx'); 
        
        //firebase server url to send the curl request
        $url = 'https://fcm.googleapis.com/fcm/send';
 
        //building headers for the request
        $headers = array(
            'Authorization: key=' . FIREBASE_API_KEY ,
            'Content-Type: application/json'
        );

        //Initializing curl to open a connection
        $ch = curl_init(); 
 
        //Setting the curl url
        curl_setopt($ch, CURLOPT_URL, $url);
        
        //setting the method as post
        curl_setopt($ch, CURLOPT_POST, true);

        //adding headers 
        curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
 
        //disabling ssl support
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
        
        //adding the fields in json format 
        curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($fields));
 
        //finally executing the curl request 
        $result = curl_exec($ch);
        if ($result === FALSE) {
            die('Curl failed: ' . curl_error($ch));
        }
 
        //Now close the connection
        curl_close($ch);
 
        //and return the result 
        // return $result;
        render($result);exit;
    }