Why isn't work

Question

Where is the problem
https://code.sololearn.com/c4B2eRYfEzT7/?ref=app

Answer 1

I've fixed quite a few issues:
https://code.sololearn.com/ceF4jFVt59wH/?ref=app

Answer 2

obj.addbook(amount)

addbook is a method of object of class called catalogue