Method less

tests/autotester/json11.hpp:370–370

    int int_value() const override { return m_value; }
    bool equals(const JsonValue * other) const override { return m_value == other->number_value(); }
    bool less(const JsonValue * other)   const override { return m_value <  other->number_value(); }
public:
    explicit JsonInt(int value) : Value(value) {}
};