Closures!!!
It took me a while to understand1 but this run through has really cemented how I look at them and just working with them in different tutorials.
For example, I had no idea what the section on “Closures as parameters” actually was saying. Now I can read the code and understand it.

I’m really excited and proud of myself! I did get a little too excited when I start the trailing closure syntax, but I can see where I went wrong versus just scratching my head about it.
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I’m still working towards understanding. ↩︎