Define a method Book.all
that works like this:
Book.new('gravitys rainbow', ['thomas pynchon'])
Book.new('mason & dixon', ['thomas pynchon'])
Book.new('calvin and hobbes anthology', ['bill watterson'])
after i do this above,
I would expect that calling Book.all
would return an array with the 3 newly created books inside
[<Book @title='gravitys rainbow'>, <Book @title='mason & dixon'>, <Book @title='calvin and hobbes'>]
and that
Book.all.first.class == Book
# => true