Node.js util.inherits issue

I'm trying to create a class that extends EventEmitter and i'm using the same example that is on the Node.js documentation.

var events, http, https, util;
events = require('events');
util = require('util');

function Feeder() { events.EventEmitter.call(this); }

util.inherits(Feeder, events.EventEmitter);

Then when I create an instance of the the Feeder object I get the following error: feeder = new Feeder();

TypeError: object is not a function