Hello! Different than Td0g's, as there I think is an issue with the server that checks submissions. It's spinning for me as well when I try to submit, on this and other challenges in the course.
A developer is looking into this.
Thanks for posting!
update: This actually isn't and wasn't a course problem. No other reports--and we have a fair number of users doing this course--and there seemed to be an issue solely with my account. The server issues were non-existent when a developer checked, and when I used another account things worked.
It's likely "extensions or browser settings":https://support.codeschool.com/help/trouble-shooting-challenge-and-submission-issues . Change those so things work, and you should be set!