https://underscorejs.org/docs/underscore-esm.html

https://coffeescript.org/annotated-source/lexer.html

https://backbonejs.org/docs/backbone.html

I wish code like this was more common. Over and over, I've heard fellow programmers reply with something along the lines of "well it should be obvious what it does! just look at the name and implementation - all you need is right there", when it was suggested that they add documentation to their implementations. What never seems to quite get across fully is that, yes, the code is all there, and it may even be clean and fairly readable, but the inherent complexity is such that only programmers experienced in subject X will ever have a chance of actually understanding it.

"So, what? If it's that complex, then maybe only programmers who are that experienced should attempt to read and/or contribute to it"* is another sentiment I've seen expressed. Of course, this misses the logic that, in order for such programmers to exist, they have to learn from somewhere, and start from something.

And how will we ever have programmers experienced in that subject

I assume you mean "on the side" and I agree, it's a game-changer. Normally I find literate programs to be tedious to read but simply changing the layout makes a huge difference.