void *dlist_insert(Dlist *,void *,int) ;
void *dlist_insert_sorted(struct dlist *list, void *new_elem, int (*sorter)(void *, void *));
void *dlist_insert(Dlist *,void *,int) ;
void *dlist_insert_sorted(struct dlist *list, void *new_elem, int (*sorter)(void *, void *));