Tip:
Every time you open a notebook, you must run all of the cells starting from the top. That is where the assets are imported and the workspace is created.
can youpost screenshot of the complete error you got?
not defined error usually occurs either because you didn’t run down a code mentioning book_title or when you defined book_title code, you might have defined the code incorrectly as per my understanding
that section required you to first mention
book_title = Name of the book
then in the next exercise you needed to use f’string to defined Book Title = {book_title}
In the above code if you have placed f’string correctly, you error should resolve