ValueWriter(const Value& _value, const Writer& _writer)

       ValueWriter(const Value& _value, const Writer& _writer)

  	: value(_value), writer(_writer) {}

  	: value(_value), writer(_writer) {}

       virtual void write(std::ostream& os) {

       virtual void write(std::ostream& os) {

       }

       }

     private:

     private:

       const Value& value;

       const Value& value;

       Writer writer;

       Writer writer;

     };

     };