[gumby]

That conditional would be checked, then if it failed, checked again after the normal case has run, in order to choose the arm to follow.

Not a huge deal execution-time-wise, but from a reader’s PoV, the way I write it says, “ok, the special cases don’t apply to the body so I don’t have to worry that the index will be out of range (or whatever) and can just focus on the logic”.