Error while running app js application

error message

I just started with APP JS and I followed the guide given on http://appjs.org/
to create a sample application.

This is the error I get when I use the command:

node --harmony app.js


/home/rushabhhathi/Desktop/desktop-app/app.js:7
app.serveFilesFrom(path.resolve(__dirname, 'public'));
                   ^
ReferenceError: path is not defined
    at Object.<anonymous> (/home/rushabhhathi/Desktop/desktop-app/app.js:7:20)
    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)

Any clue in this direction would be welcome!
Many thanks.