Authors gets defined twice

[Mayse]

ex. 24 asks to "Write the function (authors books) that returns the authors of every book in books as a set." but later on after ex. 30 "(def authors #{china, felleisen, octavia, friedman})" data is introduced for testing purposes which gets masked by the previous function definition.

[baobabKoodaa]

I'm having issues with this as well.