protected:
ex derivative(const symbol & s) const;
bool is_equal_same_type(const basic & other) const;
bool match_same_type(const basic & other) const;
unsigned return_type() const;
protected:
ex derivative(const symbol & s) const;
bool is_equal_same_type(const basic & other) const;
bool match_same_type(const basic & other) const;
unsigned return_type() const;