[DNM] Compare format-black vs. format-yapf-facebook

[peternowee]

Example for discussion in pydot#265.

-/left side: black -l 79 --skip-string-normalization # 21.5b1 with some manual corrections.

+/right side: yapf # 0.31.0 with .style.yapf (below) and some manual corrections.

based_on_style=facebook
blank_line_before_nested_class_or_def=True
column_limit=79

Both started out from master:

           --> format-black
         /            ^
master--             / this PR is just to compare the two results
         \          /
           --> format-yapf-facebook

(so not master -> format-black -> format-yapf-facebook).