adding some code review comments

You don't need to accept this pull request, but take a look at the comments above functions for some notes on optimizing your functions/readability. 

Let's also plan on taking a look at your file structures - I wanted to do some code review on your flask app and database model, but I saw lots of duplicated code and files and was unsure which files were relevant. I think using branches may be helpful for you in this case - we can go over some of it tonight.

-Mercedes