python: some unclear parts in "Sharing data between callbacks"

[daattali]

https://dash.plotly.com/sharing-data-between-callbacks

In the section that says "There are three main places to store this data" the following 4 examples don't neatly match up with these 3 concepts. (1) There's 4 instead of 3 examples even though it says there are 3 examples, and (2) the titles of the examples are vastly different from their explanation above. It caused me to scroll up and back down and back up several times to try to make sense of it