ex series(const relational & s, int order, unsigned options = 0) const override;
ex subs(const exmap & m, unsigned options = 0) const override;
bool has(const ex & other, unsigned options = 0) const override;
ex series(const relational & s, int order, unsigned options = 0) const override;
ex subs(const exmap & m, unsigned options = 0) const override;
bool has(const ex & other, unsigned options = 0) const override;