public function sendNotification($registrationIds,$title,$message)
    {
        $msg = array
        (
            'body' => $message,
            'title'     => $title,
            'vibrate'   => 1,
            'sound'     => 'default',
            'largeIcon' => 'large_icon',
            'smallIcon' => 'small_icon'
        );
        $fields = array
        (
            //in array ['23143252','329AJK398420380]
            'registration_ids'  => $registrationIds,
            'notification'          => $msg
        );

        $headers = array
        (
            //server-key firebase
            'Authorization: key=' . config('firbase.server_key'),
            'Content-Type: application/json'
        );

        $ch = curl_init();
        curl_setopt( $ch,CURLOPT_URL, 'https://fcm.googleapis.com/fcm/send' );
        curl_setopt( $ch,CURLOPT_POST, true );
        curl_setopt( $ch,CURLOPT_HTTPHEADER, $headers );
        curl_setopt( $ch,CURLOPT_RETURNTRANSFER, true );
        curl_setopt( $ch,CURLOPT_SSL_VERIFYPEER, false );
        curl_setopt( $ch,CURLOPT_POSTFIELDS, json_encode( $fields ) );
        $result = curl_exec($ch );
        curl_close( $ch );

        return $result;
}