forked the main site so I can upload code for HW

[iampei]

I uploaded all 3 sessions - simple calculator: added divide by 0 error.

[codedragon]

Because you are raising a ValueError, and not including a message no error will show up on your page. You should either include a message:

 raise ValueError("Please use 'add', 'subtract', 'multiply', or 'divide'")

or catch the ValueError in your application function, and address it there. Also, it shouldn't be a ValueError, but probably a NameError, since these are not numbers.

[codedragon]

Works, yay! A couple of notes, Cris had asked to include a readme, which is a good habit to get into. Also, it is best to have tests. In a small app like this, it may seem like overkill, but when you start trying to refactor larger code bases, you will be glad to be in the habit of writing tests. Finally, I would think about how you might refactor your app to allow more inputs (2+3+5, for example).