Method and_then

test-app/runtime/src/main/cpp/ada/ada.h:2941–2943

    !defined(TL_EXPECTED_GCC54) && !defined(TL_EXPECTED_GCC55)
  template <class F>
  TL_EXPECTED_11_CONSTEXPR auto and_then(F &&f) & {
    return and_then_impl(*this, std::forward<F>(f));
  }
  template <class F>
  TL_EXPECTED_11_CONSTEXPR auto and_then(F &&f) && {
    return and_then_impl(std::move(*this), std::forward<F>(f));