ex subs(const exmap & m, unsigned options = 0) const override;
void archive(archive_node& n) const override;
void read_archive(const archive_node& n, lst& syms) override;
ex subs(const exmap & m, unsigned options = 0) const override;
void archive(archive_node& n) const override;
void read_archive(const archive_node& n, lst& syms) override;