int ldegree(const ex &s) const override;
ex coeff(const ex &s, int n = 1) const override;
ex collect(const ex &s, bool distributed = false) const override;
int ldegree(const ex &s) const override;
ex coeff(const ex &s, int n = 1) const override;
ex collect(const ex &s, bool distributed = false) const override;