The servers are all sandboxed and isolated to you as an individual learner. What problems did you find? Feel free to email me at artur@codecademy.com.
I'm having trouble with - and = which look almost the same to my not so great vision.
https://www.dropbox.com/s/dtyrq7jlao350br/Screenshot%202015-...
By the way, thanks to the codecademy team. Cool stuff.