17 Language support library [support]
namespace std {
  template<>
  struct coroutine_handle<noop_coroutine_promise>
  {
    
    constexpr operator coroutine_handle<>() const noexcept;
    
    constexpr explicit operator bool() const noexcept;
    constexpr bool done() const noexcept;
    
    constexpr void operator()() const noexcept;
    constexpr void resume() const noexcept;
    constexpr void destroy() const noexcept;
    
    noop_coroutine_promise& promise() const noexcept;
    
    constexpr void* address() const noexcept;
  private:
    coroutine_handle(unspecified);
    void* ptr;  
  };
}