Class excessive_nesting

example/json.cpp:27–34

    // during the parse.
    template<typename Iter>
    struct excessive_nesting : std::runtime_error
    {
        excessive_nesting(Iter it) :
            runtime_error("excessive_nesting"),
            iter(it)
        {}
        Iter iter;
    };


    // The only globals we need to parse JSON are: "How many data structures