extern jb_err enlist_unique_header (struct list *the_list, const char *name, const char *value);
extern jb_err enlist_first (struct list *the_list, const char *str);
extern jb_err list_append_list_unique(struct list *dest, const struct list *src);
extern jb_err enlist_unique_header (struct list *the_list, const char *name, const char *value);
extern jb_err enlist_first (struct list *the_list, const char *str);
extern jb_err list_append_list_unique(struct list *dest, const struct list *src);