Funny enough, I've known it exists. I've never really found much of a use case for it. Where I have found it "might" be useful is rare one-off APIs. If I were t

Funny enough, I've known it exists. I've never really found much of a use case for it. Where I have found it "might" be useful is rare one-off APIs. If I were to write a wrapper for one API to work with an equivalent API, then maybe I might use this. But for one-off things, it's not important enough to use IMO. On the other hand, I remember reading it and thing it was a bit-flip operation since it's in <functional> instead of <tuple>. So I was quite surprised to find that it's really much more like a tuple operation (which is template magic) than bit flipping (at runtime, or possibly also constexpr)