Method operator[]

example/proxy.cpp:25–34

    }

    proxy
    operator[](string_view key)
    {
        object* obj;
        if(jv_.is_null())
            obj = &jv_.emplace_object();
        else
            obj = &jv_.as_object();
        return proxy((*obj)[key]);
    }

    proxy
    operator[](std::size_t index)