syntax error, unexpected '->' (T_OBJECT_OPERATOR), expecting ']'

Hi Awesome People

I was following Laracast's Api course

i'm getting following error

FatalErrorException in LessonsController.php line 19:
syntax error, unexpected '->' (T_OBJECT_OPERATOR), expecting ']'

My Controller is

<?php

namespace App\Http\Controllers;

use App\lesson;
use Response;
use Illuminate\Http\Request;

class LessonsController extends Controller
{

    //fetch all and pass a metadata 'data' 
    public function index() {

        $lessons = Lesson::all();

        return Response::json([

            'data' => this->transform($lessons)

        ], 200);
    }


    //fetch by id
    public function show($id) {

        $lesson = Lesson::find($id);

        if(! $lesson) {

            return Response::json([

                'error' => [
                    'message' => 'No Response Please Try Again'
                ]

            ], 404);
        }

        return Response::json([
            'data' => $lesson->toArray()
        ], 200);
    }


    //transform the lessons data and return only requried fields
    public function transform($lessons) {

        return array_map(function($lesson) {

            return [
                'title' => $lesson['title'],
                'body' => $lesson['body'],
                'avtive' => $lesson['completed'],
            ];

        }, $lessons->toArray());
    }
    
}

Thank You