Indexing square brackets split on 3 lines

[ikamensh]

Describe the style change
I have an assert statement that checks a condition on the last element in an array. To me what black does to the statement makes it less readable:

assert self.ref_transitions[-1].terminal.all(), "Last ref transition must be terminal."

Examples in the current Black style

assert self.ref_transitions[
    -1
].terminal.all(), "Last ref transition must be terminal."

Desired style

assert (
    self.ref_transitions[-1].terminal.all()
), "Last ref transition must be terminal."

# OR

assert self.ref_transitions[-1].terminal.all(), (
    "Last ref transition must be terminal."
)

Additional context

I think operation of taking [-1]th element is best visible with brackets and number grouped. Having to search them across a diagonal on 3 lines is tough.

[felix-hilden]

Hi! The bracket break is tracked in #236, and assert formatting in #348. Therefore this could be considered a duplicate, if you think they satisfy your style proposal!

[JelleZijlstra]

As @felix-hilden said this is a duplicate of various older issues.