Function operator==

3rd/nlohmann_json/include/nlohmann/json.hpp:6444–6447

    template<typename ScalarType, typename std::enable_if<
                 std::is_scalar<ScalarType>::value, int>::type = 0>
    friend bool operator==(const_reference lhs, ScalarType rhs) noexcept
    {
        return lhs == basic_json(rhs);
    }

    /*!
    @brief comparison: equal