* Use f-strings instead of .format()
* Code block language marker fixes
* Make example code blocks syntactically valid Python
* Run all python code blocks through black
https://github.com/scop/misc/blob/master/black_markdown.py
* Add some missing code block language markers
* Use shell language consistently to mark shell code blocks
* Undo folding of some example dicts
* Remove outdated OrderedDict comments per Python 3.7, replace with plain dict
