At this point, we've covered and implemented a large number of changes to our application. It's understandable that something might be broken for you, so let's run through a quick checklist to make sure we haven't missed any trouble spots that might be preventing your app from running properly:

• Make sure you've installed all of the required modules for this chapter and that they are saved to your package.json file. This includes mongoose, async, and md5.
• Make sure the appropriate dependency modules are being required at the top of each of the module files they are used in.
• Make sure you remember to launch mongod in another terminal instance whenever you run the application.
• When in doubt, pay attention to the stack trace output that Node is giving you in your terminal when it fails, as it is typically pretty obvious what's wrong.
  It will also give you the filename and line number of the offending module.
• When all else fails, execute console.log everywhere!

Next up, let's update the stats helper module to use it parallel as well, so we can get some real stats for the application.