Im confused???

Question

Why is my code not working. Ugh it's so annoying.
Link: https://code.sololearn.com/cQhc4Dkbl51r/#cs

Answer 1

i don’t see any implementation of ‘Book’ class as well. Kaba K

Answer 2

The spelling of "author" is inconsistent between lines 14 and 21. Fix it in line 14.