[delta_p_delta_x]

Standard library modules: https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2022/p24...

I have thoroughly forgotten which header std::ranges::iota comes from. I don't care either.

[m-schuetz]

Last time I tried, modules were a spuriously supported mess. I'll give them another try once they have ironclad support in cmake, gcc, clang and Visual Studio.