+ void print_indexed(const print_context & c, const char *openbrace, const char *closebrace, unsigned level) const;
+ void do_print(const print_context & 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;
+ void validate() const;