Method operator()

include/pybind11/pybind11.h:3346–3346

NOLINTNEXTLINE(readability-const-return-type) // PR #3263

    using result_type = decltype(*std::declval<Iterator &>());
    // NOLINTNEXTLINE(readability-const-return-type) // PR #3263
    result_type operator()(Iterator &it) const { return *it; }
};

template <typename Iterator, typename SFINAE = decltype((*std::declval<Iterator &>()).first)>