Re-think multiline slashes

[dannysepler]

python black does this:

assert some_really_really_really_long_thing == some_other_really_really_really_long_thing, "this is an error message"

...

assert (
    some_really_really_really_long_thing == some_other_really_really_really_long_thing
), "this is an error message"

instead of using slashes, and i think that's a pretty good idea. plus it helps with inline comments which currently are syntactically breaking