unsigned upper_precedence) const;
virtual expair split_ex_to_pair(const ex & e) const;
virtual expair combine_ex_with_coeff_to_pair(const ex & e,
unsigned upper_precedence) const;
virtual expair split_ex_to_pair(const ex & e) const;
virtual expair combine_ex_with_coeff_to_pair(const ex & e,