The member impls-for<schedule_from_t>::complete
is initialized with a callable object equivalent to the following lambda:
[]<class Tag, class... Args>(auto, auto& state, auto& rcvr, Tag, Args&&... args) noexcept
-> void {
using result_t = decayed-tuple<Tag, Args...>;
constexpr bool nothrow = (is_nothrow_constructible_v<decay_t<Args>, Args> && ...);
try {
state.async-result.template emplace<result_t>(Tag(), std::forward<Args>(args)...);
} catch (...) {
if constexpr (!nothrow)
state.async-result.template emplace<tuple<set_error_t,
exception_ptr>>(set_error, current_exception());
}
start(state.op-state);
};