Method start

test/exec/test_trampoline_scheduler.cpp:44–54

      int      counter_;

      void start() & noexcept
      {
        if (counter_ == 0)
        {
          ex::set_value(static_cast<Receiver&&>(rcvr_));
        }
        else
        {
          ex::set_error(static_cast<Receiver&&>(rcvr_), try_again{});
        }
      }
    };

    template <ex::receiver_of<completion_signatures> Receiver>