fixed formatting of python code examples

This is for sure controversial :D

I have changed the formatting of code examples a little bit (I found non-multiple of 4 indentations 🙈 ). Because I'm lazy I ran all the examples through black and this of course changed a tiny bit more than just inconsistent indentations. I can understand if that is too much to bear for such a PR. In this case you can also regard this PR as an issue and fix only the indentations (yourself) :)

Cheers!

side note: I really like the "no more discussions about code style"-part of black, a lot of projects are using it these days!