Reformat Python code with yapf. (#2589)
I've add an option to yapf to do what we want for long lines, see
https://github.com/google/yapf/pull/1177. We can now have a real Python
formatter, yay!
To make this PR, I ran my modified yapf over the repository, then looked
over the full diff. Where yapf was mangling the param list of long
function decls/calls (mostly kernels), I manually added # to put
linebreaks where we want. I fixed up other formatting too -- mostly
adding or removing a trailing comma from lists.
Overall, trailing # was sufficient to get formatting similar to our
current code. I didn't have to disable yapf anywhere.
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Co-authored-by: Phil Tillet <phil@openai.com>