Method nest

include/exec/async_scope.hpp:831–835

      template <sender _Constrained>
      [[nodiscard]]
      constexpr auto nest(_Constrained&& __c) -> __nest_sender<__decay_t<_Constrained>>
      {
        return __nest_sender<__decay_t<_Constrained>>{&__impl_, static_cast<_Constrained&&>(__c)};
      }

      template <__movable_value _Env = env<>, sender_in<__spawn_env_t<_Env>> _Sender>
        requires sender_to<__nest_sender<__decay_t<_Sender>>, __spawn_receiver<_Env>>