C++20 provides symmetric transfer ([P0913R1](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0913r1.html) [1]) - a mechanism where `await_suspend` returns a `coroutine_handle<>` and the compiler resumes the designated coroutine as a tail call. Coroutine chains execute in constant stack space. `std::execution`