Method set_value

include/exec/task.hpp:390–395

      using receiver_concept = receiver_tag;

      void set_value() noexcept
      {
        // Resuming the continuation of the parent coroutine will cause it to continue
        // executing on the new scheduler.
        STDEXEC::__coroutine_resume_nothrow(__parent_);
      }

      void set_error(std::exception_ptr __eptr) noexcept
      {