node.js, need help to fix this bug "TypeError: object is not a function"

I am learning node.js. trying some demos on cloud9. the demo is very simple, only 2 js files. I checked line by line, everything seems fine. please help me to debug it.

  1. resource.js file.

            var util = require('util');
        var EventEmitter = require('events').EventEmitter;

        function Resource(m){

            var maxEvents = m;
            var self = this;

            process.nextTick(function(){
                var count = 0;

                self.emit('start');
                var t = setInterval(function(){
                    self.emit('data', ++count);

                    if(count === maxEvents){
                        self.emit('end', count);
                        clearInterval(t);
                    }
                }, 10);
            });

        };

        util.inherits(Resource, EventEmitter);

  2. 7-extEmitter.js

            var Resource = require('./resource');


        var r = new Resource(7);


        r.on('start', function(){
            console.log("I've started!");
        });

        r.on('data', function(d){
            console.log("    I received data -> " + d);
        });

        r.on('end', function(t){
            console.log("I'm done, with " + t + " data events.");
        });

here's the error message I got:

            Your code is running at 'http://node.myw714.c9.io'.
            Important: use 'process.env.PORT' as the port and 'process.env.IP' as the host in your scripts!
            /var/lib/stickshift/511e07b5500446f25c0001bd/app-root/data/407149/7-extEmitter.js:4
            var r = new Resource(7);

              ^
            TypeError: object is not a function
                at Object. (/var/lib/stickshift/511e07b5500446f25c0001bd/app-root/data/407149/7-extEmitter.js:4:9)
                at Module._compile (module.js:449:26)
                at Object.Module._extensions..js (module.js:467:10)
                at Module.load (module.js:356:32)
                at Function.Module._load (module.js:312:12)
                at Module.runMain (module.js:492:10)
                at process.startup.processNextTick.process._tickCallback (node.js:244:9)

You just need to remove that initialization code.

    var r = require('./resource');


    r.on('start', function(){
        console.log("I've started!");
    });

    r.on('data', function(d){
        console.log("    I received data -> " + d);
    });

    r.on('end', function(t){
        console.log("I'm done, with " + t + " data events.");
    });

And add this line in the resource.js, if you want it to be more general, you should change the function structure to allow to set the value m.

module.exports = new Resource(7);