update black version

[bjlittle]

🚀 Pull Request

Description

🎬 Take two...

Encountered unexpected minor carnage in #3864, when attempting to upgrade the black version from 19.10b0 to 20.8b1, so it was actually easier to close #3864 and start again 😉

Okay, so this was interesting... you could just leave black to do it's thing, and mindlessly accept what it generates. However, a wee bit of manual intervention is required in the case where black had previously (19.10b0) injected trailing ,'s at the end of sequences et al... which is fine in itself, but when injested by 20.8b1 it reformats it in a rather hideous way e.g., this

np.logical_and(mask_invert[:-1,], diffs_along_y)

goes to

np.logical_and(
    mask_invert[
        :-1,
    ],
    diffs_along_y,
)

🤮

In response, the manual intervention involves deciding whether the previously injected , was necessary or not, particularly if it was causing icky reformatting to occur.

Also, I ended up making acceptable but slightly subtle tuples more explicit, also in order to avoid over-blackification™️ (that's now an official term btw 😉) e.g., this

(2, 0, 1),

becomes this

((2, 0, 1),)

Meh... I'm not overly offended by it, particularly when it stops this

         self.check((3,), Index[(2, 0, 1),], [(np.array([2, 0, 1]), Ellipsis)])

transmuting into this little rose bud

        self.check(
            (3,),
            Index[
                (2, 0, 1),
            ],
            [(np.array([2, 0, 1]), Ellipsis)],
        )

---

Consult Iris pull request check list

[trexfeathers]

e.g., this
(2, 0, 1),

becomes this
((2, 0, 1),)

That change is generally quite helpful to a Python yearling like me ❤

[bjlittle]

@trexfeathers I suppose this requires a whatsnew entry, right?

If so, would you prefer me to tack it along with this PR, or raise it separately?

[trexfeathers]

If so, would you prefer me to tack it along with this PR, or raise it separately?

I hope this will be a quick one, so just include it here. Thanks!

[trexfeathers]

Great, thanks for persevering @bjlittle 🖌️ ⚫

[bjlittle]

@trexfeathers Awesome, thanks! 👍

[rcomer]

Wow, just wow. 🤯