list_append_unique
extern void **list_append_unique(void **, void *, int (*)(void *, void*));
(ns_bsd_addr_t **)list_append_unique((void **)list,
(ns_bsd_addr_t **)list_append_unique((void **)list,
list_append_unique((void **)list,
list_append_unique((void **)list,
(ns_bsd_addr_t **)list_append_unique((void **)list,