Ah, I see. That really doesn't deserve to be called an idiom, it's a clever hack. But it's nice to know about it. It seems less ugly than the walrus operator to

Ah, I see. That really doesn't deserve to be called an idiom, it's a clever hack. But it's nice to know about it. It seems less ugly than the walrus operator to me, and it doesn't leak the variable outside of the comprehension.