protected:
void print_index(const print_context & c, unsigned level) const;
void do_print(const print_context & c, unsigned level) const;
+ void do_print_csrc(const print_csrc & c, unsigned level) const;
void do_print_latex(const print_latex & c, unsigned level) const;
void do_print_tree(const print_tree & c, unsigned level) const;