I've just stated learning python as I see a lot of potential in it. So thank you for sharing this exercises. Is it possible to contact you if I have any questions?

There is an email address at the repo. You are welcome to contact the author. Thank you.

I only see a collection of exercises, but I don't see where is the proposed solution or how they are graded by difficulty or grouped by similarity. The link is the second set of exercises, there is part one.

An example of exercise is this page is to define a function to remove spaces in subslists. It gives an example with input and expected output.

At the top of each notebook, there is a link to the solution, but you may want to find your own solution.

Does anyone know of an ES6 variant of this?

Rewriting them in ES6 seems like a good idea to learn JS.