If you’re going through Intermediate Ruby, and are doing the module about serialization, I would strongly recommend taking notes in a markdown editor. I’m using MacDown, and I see the output of the markdown text immediately.
Typing a code block in YAML helps tremendously. I imagine most IDEs have support for YAML, either built in or extendable, and the formatting goes pretty far to reveal things.
Just a suggestion, since the article by Alan Skorkin is almost 10 years old, and the section on “human-readable serialization” is not necessarily very “human-readable”. LOL!
If I had more time, I’d paraphrase the resource and bring it more current…alas, I’m both lazy in the good programming way, and lazy in the bad way…LOL