Function _ATTENTION_

include/stdexec/__detail/__debug.hpp:65–66

                 " one of the declared completion signatures.")]] constexpr  //
      STDEXEC_ATTRIBUTE(host, device)                                        //
      void _ATTENTION_() noexcept
    {}

    template <class _Env>
    using __env_t = env<prop<__debug_env_t, bool>, _Env>;