As I am learning and going through exercises it is easy to forget syntax and get it mixed up in your head. I did start writing it down on paper, here is an easier way:
Having this to hand has helped me without having to backtrack through the book. There are more online if you all Google search there are some advanced ones such as:
I know a lot of people may already have their own way of taking notes but this is just another way to quickly reference.
